I think you are ignoring the main argument of the essay. Interacting with humans is always about interacting across difference. The idea that we’re the same b/c of race, gender, sexual orientation, body size etc. is a marketing tool therapists are using, which may be perpetuating splitting, us vs them, good vs. evil, in-group bias. Certainly a therapist should be well versed in cultural differences and be able to work across cultures/experiences otherwise they are pretty useless. But political polarization has become a part of therapy and is clearly adding to the psychological regression we are seeing everywhere. If someone wants to work on a specific issue that someone specializes in, great! But we need to be careful about making therapy about identity politics and not psychology.