Easy because it effected another player.
I used to play Minecraft on occasion. I eventually get bored, so I go exploring and raiding.
I was playing in a server that hadn't reset/respawned in ages. Cows were non-existant outside of personal farms. I am new to the server and it was my first playthrough so I didn't realize my leather problem until 20 hrs in. Well, I move on.
Later I explore. I come across a base camp. I go in, not griefing yet. I am impressed by the house, but after trying to open chests I find out it is protected. So, I venture down to where he kept his cows. I can't open the gate or jump the fence. Then, a lightbulb goes off. I can use a creeper to bomb the gates.
Well, I lure a Creeper in and have it destroy the gates. Well, then I kill all the cows and collect all the leather.
A few days later someone is raging and depressed in the chat. Apparently their cows were gone and explosion caused damage to their base. They literally rage quit the file saying they will never play Minecraft again because after spending months collecting they lost it all. I felt like crap, but kept my mouth shut because there were no specific rules prohibiting this in the server.
Well, a few weeks later I screw up and can't figure out how to reclaim my land. I ask in the chat and someone says they will help. Well, that person helped themself to all my bookshelves, diamonds, etc. I rage quit too. Set fire to my house and leave the server forever. (Fire spread and destroyed everything)
Never did that again.