Both buildings and bushes serves a gameplay purpose, one forcing movement and the other lowering visibility (and to some extent movement as well). Same goes for neon weapons. Shouldn't there be skill involved in spotting your opponents gear or remembering where you missed that arrow? We praise blocking, but there are many more ways to be skillful in a game.
Games strive to be equal, in the sense that everyone has the same starting conditions. Regardless of skill I can always assume that my opponent sees what I sees and have to obey to the same rules as I do. When you start altering this to your own benefit, being able to ignore various visibility issues (which are core elements in any competitive game), you're cheating, for the simply reason that not everyone has the ability do the same (within the frame of the game).
Now, that being said, the game allows you to alter it without any real consequences, and currently there is no way for us to enforce rules about this. You can't ban people on speculations and hearsay.
In short, it's cheating but we can't do anything about it.