When it comes to accessing the mainstream media discourse, academic discourse, or any similar prominent discourse that reflects on justice and politics, poor people face a double-bind that ensures their voices are permanently erased. If you grow up poor and you remain poor, your access to any of these discussions is basically nonexistent. If you grow up poor and then become educated and established enough to access and even influence these discussions, that generally means you are not poor anymore and so your perspective on class can be dismissed on identitarian grounds.
This double-bind is not true of any other identity because no other identity disappears at the same point at which you are able to meaningfully engage in the discourse. A person of color doesn’t cease to be a person of color just because they acquire the credentials and ability to become a successful writer or academic. Nor does a woman cease to be a woman when they do so. But a poor or working class person does, in a direct material sense, cease to be poor and working class once they’ve won a professorship or a stable writing gig.
Given that identitarianism is a generally liberal political grouping that has no real interest in class politics, this is not that big of an internal problem. But when practitioners of identitarianism run up against those who do have an interest in class politics, the contradictions create incredible havoc. This is especially so because identitarianism is so heavily intertwined with certain discourse norms demanding deference to (even bourgeois) members of various demographic groups. And the last thing someone interested in class politics should ever do is hesitate to harshly criticize any bourgeois discourse participant with bad arguments and opinions, especially when those arguments and opinions concern class issues.