"People are recommending a book by an author." Fixed that for you.
I'll give you the BLM, that's an instance of necessary discrimination. The rest ... if the authors advice is wrong, criticise it, if the book or person does something bad, criticise it. Don't just pick out the skin colour of the author, or of someone recommending the book, and use that as a reason why it's bad. That's racist.
[Please note I haven't read the book, and do not know the author, and am categorically not promoting either.]
I can usefully talk about MySQL because I used it in a multi-year project that pushed its performance to the limit. I cannot usefully talk about Cassandra - the most I have done with it is install it.
Similarly, I can usefully talk about the experience of a male Russian immigrant to the US. I cannot usefully say much about the experience of a black woman who lived in the US since birth - I have not lived it, all my sources would be second-hand; my listener would be best served by referring to the sources directly.
I may suggest that to find out about the experience of black Americans, it's best to refer to the words of actual black Americans.
Absolutely.
And to say "this opinion is not grounded in experience" is a worthy note, but doesn't make their conclusions wrong.
As a generality people suffering a situation aren't able to take a measured approach - emotion gets the better of us - so it's not just a case of experiencing a situation. Not being subject to something doesn't discredit your viewpoint.
If you tell me I need to do sharding to improve my database performance, or whatever, and I say "this is a database of Chinese people, your opinion is invalid as your not Chinese" then I'm just being xenophobic.
People can have way more in common with others of different skin colour than they have with someone of the same colour. It's a people issue.
Focusing on segregating people's arguments by skin colour, rather than by validity of their arguments is so antithetical to the whole object of removing unnecessary discrimination that's why I felt I needed to comment, and I stand by that comment.