That's an exception. Rap music is very prevalent in today's society, and almost all of the subject matter deals with rape, killing, and selling drugs. You basically had to go back to the '90s to find an example.
I did not have to go back to the 90s to find just this example; I picked it because it was a critique by a sitting U.S. president, something that is quite rare and notable in any era.
Critiques of rap music have been a not uncommon phenomenon in the years since:
It's ironic (or actually, fitting) that you claim "I had to go back to the 90s" to find an example, because your perception of rap music seems to be stuck in the 90s, back when it faced peak critique and backlash. That we see less such critique today does not indicate that rap music has gotten a pass, but rather, that rap music has softened since what you perceived it to be in the 90s.
I don't know all of the top rap songs in 2018, but I'm pretty comfortable asserting that the majority (nevermind "almost all") do not deal with "rape, killing, and selling drugs".
I linked above to this Eminem story, but it's worth re-mentioning here: Eminem's peak work had extremely controversial lyrics; today, he's ripped for being lukewarm and for using the f-----t word, which was definitely not as verboten as back in the 90s and early 2000s: https://www.billboard.com/articles/news/pride/8473186/eminem...
