You're talking about late 80's early 90's.
Once the 90's got going it didn't matter if the radio was fair. They're going to play who is hot.
So if....let's say BIG sold 4 mill....you're going to hear him on the radio. If Outkast sold 3 mill....if Pac sold 5 mill....if Wu sold 4 mill....Jay, Nas, whoever.
People (not you, I mean in general) have a hard time reconciling the fact that at one point you could actually be as lyrical as you want, and still receive radio play and mainstream coverage. Nowadays if it's on the radio or in the club there's almost a disclaimer like

"well, this ain't meant to be taken seriously".
Anyway, to flat out say "the radio hasn't changed" is

as hell. Like I said, play a Hot 97 mix from around let's say '96....and then compare it to the mix Flex threw on during that whole Drake reference track fiasco.
Fred.