Some people enjoy watching streams of games they enjoy/have an interest in purchasing but don't want to follow that specific channel (for whatever reason).
However, there's a certain little pop-up that covers the bottom portion of the stream, pointing at the follow button, that says "Come here often? Come back to [insert Streamers name here] channel FASTER by hitting that follow button" (with a bunch of hands pointing down at the follow button like we can't see it).

See, some of us just want to watch a stream, chill out and not feel pressured to follow/sub/whatever and I wouldn't have a problem with the pop-up so much IF it only showed up once per stream .. but it seems to show up every few minutes.. pressuring you to follow.. insulting you for not following.. why haven't you followed?.. you're still here, you should follow..
Follow..
Follow..
FOLLOW NOW!!!
WHY HAVEN'T YOU FOLLOWED YET?? You JERK!!!...
...
MAYBE... because everyone has follow alerts. So, IF you follow then you announce your presense, which the streamer tends to try to strike up conversations, and you feel pressure to say more... which is fine and dandy. It's kind of the point of broadcasting yourself. You want interaction. but sometimes, as a viewer, you want to just lurk, and the constant pressure to follow does a number on those with social anxiety who want to .. just Lurk