Going by that sentiment...they should never, ever make another Thor movie. LOL (I laugh, but I'd be okies with that)
The widely varied personal feelings of the T'Challa/BP fans side...a lot of other people/critics (depends on where you look) have said that technical issues aside, it is certainly one of the better Marvel movies in the recent while and ostensibly because Coogler and Co. dared to write a story that went against "type" and felt emotional on many levels.
As someone who appreciates when movies go against "type" (as with the recent Batman and not so recent Joker movies) it was a a very enjoyable experience one that, having known everything for the past couple of years leading up to it, I was still very pleasantly surprised.
And while the figures aren't by some ridiculous standard, the "greatest", there's no way they could ever say that Black and Minority led films cannot/will not sell.