I think this is the logical leap that people aren't understanding. Generalizing means assuming things about individuals based on their group membership: OP wasn't saying it's a moral failing, but that it leads to inaccurate assumptions when applied to the heterogenous group in question.

What's the analogy to using the term "the masses"?

The morality and intent is irrelevant to my core assertion. A criticism of contravariance (if that makes it clearer) followed by a usage of it is unexpected hypocrisy, which is ironic.