In the case of Identity Politics, the problem of the Democrat approach was their assumption that White Americans would not form an identity group and someone wouldn't capitalize on it.
The problem of Lefty identity politics is they forgot what the largest single quasi-ethnic group is. But even in terms of ethnic identity,
Trump outperformed previous republicans among non-Whites.
They relied on the racial animosity towards the cishet white male, and forgot the cishet white male votes, so does the cishet white woman, and they didn't even have their identity groups shored up.