That’s….a really good question. I don’t think it’s unique to Doctor Who fans though (look at what happened to Star Wars fandom!) I think maybe it’s a combination of usual fannish entitlement (I have that too, I think most folks do…), dislike of Moffat as a person, and just general Internet exaggeration.
It can get a little annoying though, especially on GB where everything is exaggerated to heck and also requires several exclamation marks