Because those two comedians aren't that funny to many of us and the implication is that they got paid off of being either "safe" or c00ning. And in what I posted before you'll see that black comedians all deal with this issue. Katt and Mike Epps just calling it out. And yes, when you say that Katt is just hating, that's a real easy way to sidestep the issue that everybody is talking about. It's logical fallacy, attacking the messenger/ad hominem.
The issue keeps coming up with Kevin Hart. Katt Williams aint the first to bring it up.
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Kevin and Tiffany choose to play the game and are being fried for it. And these all know each other, for this stuff to get out publicly might be a good sign that behind the scenes a lot more comedians are talking about it.