Saying it is For <group> implies it is not for other groups.

Again, realistically, how many white people would pay for a platform like this? If you think the number is substantial you are delusional. For starters, its being marketed "for black people", its all black content, and other platforms e.g Netflix already have content from black creators (albeit not as focused)

Having said that, they do not need white people to sub to build a viable business. I think it could work - the real secret sauce will be in securing great content naturally. But positioning your business as "$X for black people" does pigeon hole their potential market quite a bit.