Streamers are an important part of the marketing machine for Blizzard, and to be quite honest virtually any game in today’s age. It promotes visibility and exposure of what they want to other people.
If you want to argue the list should be expanded? I mean, I get it, but I think the list is pretty expansive already.
But anyone? What value does Blizzard get out of it if I donate to my buddy who only has 4 followers?
Why can’t you just support the streamers that you like without a carrot on a stick to do it? Oh right you don’t care about the streamers.