Also, everybody does it. Every major brand already has many thousands of followers with questionable names in clearly irrelevant locations, and this on a platform where such shenanigans are visible to everyone.

There's no reason to believe upvotes, which are less visible to other users, are bought at lesser scale.

When everybody does it, it's hard to single out any one actor as bad.

I get your point but do you think that massive brands like McDonalds would take this path to show you a hidden ads about their brand. no. They can pay millions to blast you their McDonalds cups on TV ads. When these kind of companies want to start to put ads on a new media they have 6 or 7 figures budget. They don't give a damn about paying a 100USD gig to have their McDonalds cups's post on the front page for 3 hours. They want their McDonalds cups on the front page ALL the time.