Plenty of people would refer to Guru as "Gangstarr" before distinctions between producer and MC were made, so my vagueness is all fairly appropriate.
There is no real purity war. But I've always had issues with the older underground hip-hop movement which always had this attitude of "Let's not bother, the mainstream ruins everything, let's do what we do outside of everyone else's input", and those who are technically mainstream artists, but try to do something unique that makes them stand out whilst still viewing themselves as part of the mainstream.
Essentially, you get locked in a strange fiasco of choosing artists to identify with. For example, in '05, underground people were NOT ALLOWED to enjoy Cam'ron & The Diplomats (and if then, you enjoyed Juelz, almost begrudgingly). Now of course, Max B-era Jim Jones, and Cam'ron are common reference points, but years ago, you could not CONVINCE anyone that what Cam was doing had more in common with say, Lord Finesse and Kool Keith than just being another rapper from NYC who rhymed about drugs and guns.
So when a rapper is going out of his way to produce this image that is "Anti-Rap", and his content isn't that 'progressive' as his image pronounces... I find it a little too much. And as I expected, the fans of him automatically run into the cliches of "THIS IS REAL MUSIC, FUCK ALL THE LIL' WAYNE, LIL' B, SOULJA BOY GARBAGE!" because they buy into the abstraction more than the themes of the music