It's not a legacy...
There was a time when guys like Moon, Cunningham, Evans, etc were legit greats and they played the position equally as well ad their white peers.
As the game changed in the early 00s, the media became FASCINATED by the idea of a black QB actually winning something...Doug Williams won a SB in 87 as a back up, but if anyone recalls the HYPE around McNair & McNab & Vick it was crazy. The media couldn't keep their pants on...but if you actually watch the game evolve, if you even played college FB, you know the position is really a full time mental job (the physical attributes are a given or you wouldn't be playing), and that's where the evolution of the 'black' QB stops.
With the exception of Mahomes, there isn't and hasn't been since the days of Warren Moon (McNair to a lessor extent) a black QB that could call out protection, read a defense, run thru a 4 route progression and deliver a pass from the pocket. This includes Russell Wilson.
Think of today's black QB....Lamar, Fields, Hurt, etc. Their success passing, as was the case w Wilson & McNabb, came from broken plays or scrambling. That is certainly a form of QB play, but not one that will ever likely lead to success in the big game.
So, how can it be a legacy when the pedestal belongs to Brady & Montana and there isn't a black QB that plays the game that way? It's more akin to reinventing the position of QB in a way congruent to the intellectual abilities (or limits thereof) of the modern black QB, and comparing the new style of play to traditional black QBs (those that were equally gifted as their white peers) of yesteryear.