The online is the exceptional part of the game, without it I wouldn't bother with it if I were you. It's possible but it would extend the game quite a bit and this communal feelig of building paths and working with other people you don't even see all goes out the window.
Regarding, peoples stuff all over the place, it's done in a limited way so there is no mess as far as I can see and you can delete something if it bothers you. I have had to only delete a handful of structures mid way through but that was not to avoid mess but to make way for my own paths. It had some kind of algorithm where things appear in your world as if it was you who judged the spot, perhaps the ammount an structure or object gets used. It works, trust me. I've also only seen one instance of trolling in 45 hours and they failed for reasons I can't spoil.
It's masterful, I can't recommend it but I can say it is one of the best games I've played all year, easily the best sony 1st party since GoW and the most addicting since the early days of minecraft before it was taken over by kids. It's not reaply like any other game but feels like a conbination of every third person genre mixed with some strategy games and the cutscenes of a high budget TV show. It is the closest I've seen an RTS game becoming a third person action game I can remember playing and all the things the mix create something that feels new. It would be a shame to miss out on this.
Thanks, sounds good. I'm just afraid of spoilers everywhere like I had in Dark Souls when starting the game a few months after it was out. The online didn't work very well for me there as any help I summoned would kill the boss in 10 seconds while getting invaded by high level players was zero fun.
Hopefully Death stranding is a lot smarter with later starting players.