I think part of the issue with streamers being mobbed is many times streamers (who are advertising) a game get attention from a game employee maybe have them as a guest on their stream( free exposure for the game and new players means$$ for said game) so the streamer fans see them as a influence for the game they play. Because is recent years in western games devs don't pay attention to their players anymore. There is no communication with them on a regular basis. So the streamer is almost a go between gamer rep.