Mos Def is not saying anything unheard of. Even he had to step away from the scene because he was becoming a pop artist. Was he doing it intentionally, no. Though once you reach a level of success, it does not matter what you sound like, because the music becomes a tool to sell to the masses...because it's popular. Mos' music was everywhere when I was a teenager. And so was Mos. Movies, shows, video games...once you have made that transition, you're pop.
The misunderstanding people have about pop music is that it has a certain sound. Completely untrue. This may something to do with the backlash against disco way back; disco sold, and in those clubs is where you could get your music popular, faster than just trying to get mainstream through radio.
Pop Music does have a sound.
Go listen to "Hit me Baby One More Time", "Bye Bye Bye", "Complicated" and then "In Da Club".
All 4 are popular songs, but it's very clear what is a Pop song.
Pop music originated as 1950s youth music based on RocknRoll, with RocknRoll itself being an hybrid genre of Blues, Doo Woop and field songs. It was upbeat, up tempo, formulaic songs with a clear song structure.
Once RocknRoll died as a genre, it was replaced with variations of Rock, RnB and Pop music.
Pop Music as a genre is formulaic, simple songs that have an amorphous, malleable sound. It could be an RnB song, it could be a Rock song, it doesn't have clear genre conventions. Like what the fuck is Steely Dan? Are they RnB singers, Rock stars, Jazz musicians? If you can't clearly identify what it is, it's Pop Music.
Then came along electronic instruments which birthed got Electro, Techno, and Hip Hop. And from there Pop music mutated again as it took production techniques from those genres.
It looks like Pop Music as a genre is whatever popular but it's not. Pop music as a category are the most popular genres of music.
Right now, Pop artists are not the most popular artists as music listening has been democraticized. There's only Taylor Swift, Drake, The Weeknd, Olivia Rodrigo, Doja Cat and Ariana Grande.
People like clearly defined genres and genre artists that have a vision. Pop music has died as media consumption is no longer mono-channel.
Playboi Carti is one of the most popular artists out and he's clearly a Hip Hop artist. Same with Travis Scott. Nobody would call them Pop despite not sounding like prime Jay Z.
People love SZA for her take on RnB.
Beyonce just dropped a House album.
Kendrick Lamar is one of the most acclaimed rappers of all time and he didn't crossover by genre hopping like Drake.