Said every MMO ever. =P FFXI and FFXIV has had their economies decimated because of them (what little economy XIV had anyway).
Not just that, but they block progress. Sometimes there are so many of them, you cant even get a hit on the dungeon boss to get credit for completing the dungeon.
Here are a couple vids I posted messing with the bots, trying to get them killed:
https://www.youtube.com/watch?v=KEVOJr1J7ZE
https://www.youtube.com/watch?v=rTa0AQI7b4s