Did someone suggest that they did? To aknowledge that these constructs retain power is not to endorse them. On the contrary, it is a necessary precursor to any attempt to revise them. If they had no power, we wouldn't be discussing them in the first place. Meanwhile, to tell people that their identities don't exist is oppression. Even if membership in that group is detrimental to them; it's simply not for you to dictate people's identities to them. It violates their self-determination, and is counter-productive to boot. Such discourse is the core of imperialism, among other vices. Ask an actual black person, and you're likely to find that what they'd like to see is not the erasure of blackness, but the expurgation of its negative aspects. I imagine the same is true of the various castes in India; at least that's the impression my various Hindu Indian acquaintances have given me. Meanwhile, as to the actual thread topic, your motives for derrogating the Jewish identity lack the putatively good intentions of your attacks on Dalit or black identity, so there's little activist solace for you there.