There are all kinds of things people can do that you might not necessarily want from your neighbors even if your houses aren't connected especially outside city limits.
Mundane things like as neighbor with german rottweilers walks his small horses off leash but doesn't pick up their poop. Maybe they only sort of listen to him and like to chase your kids or small pets.
Maybe one of the people decides they will park a trailer on the street for their mother in law for the summer that makes it hard for you to see backing out of your driveway. Or put 4 "antique" cars on cinder blocks in their front yard to work on but can't find the time and now there are rabbits that live under them and eat your garden.
Or your neighbor get chickens or small livestock next door that come alive every morning at 5a and their son decides to take up the bagpipes to play every night at 11p.
And we of course have to remember all these neighbors move in 3 years after you, and now you can't even move because nobody else wants to live next to Rottweiler guy, bagpipes guy, or the guy from hoarders storing cars on his lawn.
This is why it makes a lot of sense to have a small HOA with a handful of rules, but it still doesn't make sense to have someone with a ruler come measure your grass.
My neighborhood of over 150 lots has been terrorized by ONE SINGLE DUDE. Almost everyone is at least reasonably considerate, but it only takes one who isn't technically breaking the law to make everything kind of suck. As our local sheriff's department likes to say, there's no law against being a bad neighbor.