Electric fence seems excessive, and the fence would still have a gate that could accidentally be left open, right? That's the main issue that needs to be resolved for your neighbours sake. A long rope or a muzzle may do it. Also may be a good idea to ask what the neighbour thinks.

But someone could forget to close it, I mean. So that wouldn't really change the situation from what happened the other day, would it?
Muzzle would be in order to put cat owning neighbours mind at ease. And possibly for those who have small children since they may worry. I was thinking when he's unsupervised in your front yard, and not when you take him for walks, because then you have him supervised. The only people who would interact with him in your front yard should be friends of yours, and if you tell them why he's wearing it, they should understand.

Rabbits are very common for cats to eat, and tear apart while they're doing so. Sure they aren't the most desired prey, cats prefer birds and mice, but they still love to kill, play with, and eat rabbits also. 

The study said the majority comes from unowned cats (which is defined as cats which don't ever go into somebody's house, even if they feed them. 

"Although our results suggest that owned cats have relatively less impact than un-owned cats, owned cats still cause substantial wildlife mortality (Table 2); simple solutions to reduce mortality caused by pets, such as limiting or preventing outdoor access, should be pursued. Efforts to better quantify and minimize mortality from all anthropogenic threats are needed to increase sustainability of wildlife populations."

"The magnitude of wildlife mortality caused by cats that we report here far exceeds all prior estimates. Available evidence suggests that mortality from cat predation is likely to be substantial in all parts of the world where free-ranging cats occur. This mortality is of particular concern within the context of steadily increasing populations of owned cats, the potential for increasing populations of un-owned cats12, and an increasing abundance of direct and indirect mortality sources that threaten wildlife in the United States and globally."

Furthermore, all unowned domesticated cats were either previously owned and neglected (not fed) or descend from previously owned cats that were allowed to roam and have babies. 

Apart from the fact that like you, plenty of other people have posted about similar things, wouldn`t it be odder for someone to do a fake post like this on a video game forum than for it to be real?

Any stats for how many lives have been saved/helped by dogs over the past few thousand years?

I don't hate cats. I hate people who don't take care of their animals properly, which often includes cat owners. I have owned and loved many cats in my life, in fact they were my first pets. If I let them outdoors I would've been aware of the risks to their health and would also be responsible for any damages my cats caused to other people. But who am I to argue with selfish people who think that it is okay for their cats to be loose, damage wildlife, damage people's property, kill people's pets, and risk their own lives?

Dogs can be more destructive of their owner's property, yes, but rarely will a dog get into another person's house, while it is a common occurance with outdoor cats. 

Also it is ridiculous to assume that the cat somehow was trained to stay in the owner's lawn. The cat likely roamed quite often. That it was on the owner's property makes very little difference when just about anything has access to it. Just as I would be partly at fault for leaving the basement window open and if the cat killed my conure (an animal just as intelligent and loving as the cat) so is the owner of this cat partly responsible for his cat's death by allowing it to live a risky lifestyle. 

Normal does not make it right. As an owner of an animal you are primarily responsible for its safety. If it dies from trauma, there was always something you could've done differently. If it is a risk you are willing to make, so be it, but that was a decision you made - own up to it and learn. If you don't understand that, then you are probably one of the people who don't deserve to own living things. 

You must hate alot of cat owners and I won't take your word on that you like cats. Your bias with them says otherwise. You seriously can't expect what the majority of cat owners do to change just because you want them to. That's your opinion and it's not the social norm. Also, this a big strawman where you tried to blame the cat instead of the dog and it's owner for what happened. It distracts from the problem itself. Even from your own source, it says that the feral cats do the vast majority of the damage. That's more of a problem with people abandoning their unwanted cat or kittens than people letting their pet cat roam around. 

Those are just a few studies, there isn't general scientists consensus.
Moreover, you can see there are major flaws in them: they don't take into account the hundreds mice and rats a single cat kills during its life, and rats and mice, if let multiplicate without control are far more harmful for the environment, including, directly, as they kill their babies, and indirectly, as they destroy resources, birds and rabbits. Another flaw is that they don't consider that once a large enough population of feral cats exists, contribution of free-roaming domesticated cats to their growth becomes minimal, particularly now that more domesticated cats are neutered than in the past, and that abandoning them is frowned upon a lot more than in the past. Abandoning them is anyway a negative factor, this is totally true. Another flaw is that those studies seem to not mention that feral cats need to hunt every day to survive and thrive, while free-roaming well fed domesticated cats don't need it and often don't want to do it either, being lazier than feral ones. Most of them by the way rarely go very far from home, and many don't even go out every day.

In my town cats are generally loved and fed and while they often kill birds, they never endangered their species as a whole, it was only seagulls growing to an eccessive number that started seriously endangering other birds.

Again about rabbits, those in those videos all were either dwarf or young ones. My family owned tens, maybe hundreds cats in the last 40 years, and for many years we bred normal sized rabbits as livestock, and despite often some of them managed to escape, it happened only once that a cat of ours killed a rabbit, and a young and little one, adults always were unharmed. As I previously wrote, also some the neighbours' normal sized adult rabbits often escape, and neither my cats, nor the others in the neighbourhood ever harm them. But a rat-sized adult rabbit, moving quickly enough to be an interesting prey, surely wouldn't be safe, that's true.