How come a lot of rappers these days are starting to sound like lil wayne and male singers sound like ChrisB?

Is it popular for today's younger generation, is that what people want
to here especially little girls?
Like lil'twist, Tyga, lil chuckie and some other dudes sound like
wayne and most of male singers like Khalil, the guy that sings Kesha,
Mindless Behavior, and even some guys singing on Youtube (a lot of
comments always say they sound like CB) others starting to sound like
Chris Brown?

Is it the auto-tune or something

I used to like and was kind of obsessed with Chris Brown when he first
came out and used to go gaga over his voice but now it's starting to
sound annoying, especially hearing it from other guy's voices.