Correct me if I'm wrong, but haven't you sort of been known as "he who does it all" for a very long time now?
I think that doing everything under one label without fan backlash is probably easier when you've been known for a lot of different styles right from or close to the get go. It's like, I wouldn't personally say I know Zircon for "complextro" or "trance" or anything like that - I've literally never said something like that. I've always just said "Zircon's a cool composer, you should check his stuff out." Similar thing for other composers like Mick Gordon. I can't say I know his music for any specific style.
In the case of WillRock and many others though, a particular style does come to mind to describe them even if they do multiple genres down the road.
What happens, far as I can tell, is people release albums and EPs where most of the tracks on it can reasonably be lumped into one category. Perhaps they do another in very similar style. Then, their music evolves and they have an album of a strikingly different style and the previous fans are disappointed because they are so used to knowing what to expect from that artist. The same behavior can be observed in movie, tv, comic and video game fans. Look at the backlash DmC faced really just because the character redesign was something unexpected and people were quick to shun it at least a full year before the game even came out. People jump to the conclusion that it must be inferior when it's something unexpected and different for some reason.
From my observation, I'd say that if you've been making albums with tons of different styles on it and drew fans that way, said fans are more likely to appreciate an equal amount or greater diversity on the next album under the same artist name. Tommy Lee (and many fans) have said numerous times that Motley Crue's 94 album would have been more successful if it wasn't called Motley Crue.