The rap rock numetal era was the death blow.
Grunge era is full of respectable music. It will still be played for a long time.
The raprock/numetal stuff is embarassing. Aged as poorly as that hokey ass early rap that people will pretend to like.. but is dog shit.
Rap rock happened because rap was actually interesting snd innovative and rock wasn't anymore. It was the last ditch attempt to make rock actually relevant when it had already been waning for years and wasn't going every direction but forward. Soft rock was killing it, and yet the folks that rock wanted to appeal too didn't want soft rock.
The reason rap survived and rock didn't. (Because both of them come from the same place, and both of then were campaigned against to a large extent for YEARS) is because of the puritan campaign against both that inversely affected rock. Metal bands got called Satanist and promoting all sorts of stuff all throughout the 80s. Rap music got called music only criminals would listen to despite the fact that much of it was simple music with a conscious if not positive message, even in the early days.
The difference is that the audience for rap music didn't buy into that propaganda because well, it was nothing new for them, same old same old story of propaganda pushing against anything... let's use their terminology and call it, "urban". The folks who made the music and the folks who listened to it were used to this. rock was forced to be sanitized and when it wasn't, it was divisive if not outright vilified and THAT audience would be ostracized into obscurity or pushed towards more palatable versions. This didn't really happen to the same extent for rap.
Rap was allowed to evolve with the times and the new generation, and meanwhile everytime a rock innovation would spring up it would never be allowed to evolve both due to its fanbase being conditioned to reject anything that sounded too sanitized, nd the mainstream being too purist to allow radical new approaches. A generational divide became created that would neuter any movement beyond a certain extent. Also, the genre had arguably been oversaturated.
Eventually all the stereotypes about rap began to fade and folks realized it wss same as any other genre with some good stuff some and stuff and plenty of mixed messages, but that it was innovative and bold art that, almost by nature of its very existence was under constant suppression and ostracizing. Eventually rap was more punk than punk music, harder than metal, and edgier than grunge.
Rock music corners too often eventually fall into self parody or die on the vine, because there's always this divide. Happenened with grunge, nu metal and pop punk over the last couple decades. Its happening with rap now but thats too mainstream to fail at this time.