I'd be really interested to know when, if not from the very beginning, boasting in hip-hop became a normal thing. It just seems so natural for a hip-hop artist to do that.
The reason I'm not worried about the prevalence of boasting and diss tracks is because there are so many more topics to rap about-- while it's probable that Biggie was addressing a greater variety of topics than Rae Sremmurd and Migos are now, at least Kendrick is still talking about these things. To Pimp a Butterfly was a racial endeavor. I think unmastered unitled (or whatever) was an instrumental exploration. Just saying I wouldn't cry "doom" just yet :)
edit: Speaking of doom-- just look at MF DOOM! And Earl. And the fact that those "pop hip-hop" artists like Migos rely almost entirely on fire production skills which are more important to their audience than their absolutely bullshit rhymes.