In theory, I'm fine with some ads. Useful ads in places where it makes sense (like shopping). Small, unobtrusive ads that fill up otherwise empty space. But ads are like capitalism and cancer. They just continue to grow and grow and get worse and worse until they've utterly destroyed the thing they were meant to support. If you let them in, it's only a matter of time until they completely take over. No one has managed to do 'reasonable ads' for any great length of time.

It's just one of those things where in theory it sounds workable, but in practice it's highly destructive and corrosive towards everything.