As a long distance observer I would guess that a lot of kids in the Bronx were probably into pop smoke and maybe 6ix9ine (whose whole style was screaming and was one time aligned with 50, now seen as a disgrace obvs) and they took the axl beats style and used it as a platform for more and more aggressive flows.
Maybe it was a competitive thing - especially since a lot of them are in rival gangs who are actually trying to kill each other. So the threats have to become more and more over the top.
The producers meet the need for beats that match/stimulate the aggression and visa versa?
Also hugely important clearly is dancing, which you see in every video. Not sure the context of that, could just be that internet era kids are into these fortnite-y dances, or could just be a perennial feature of New York/US culture?