if you call everyone dude and a transfem person gets mad about it, don't get defensive. just say like "sorry, i won't do it again" and don't argue "actually it's gender neutral" or "i call everyone dude". even if you do, i guarantee she's heard that argument from someone who very much does not call people they see as women dude. i certainly have
same goes double for the word guy.
Yes, absolutely. It's a case of linguistically defaulting to a masculine form. Not gramatically (grammatical gender is largely vestigial in contemporary English outside of personal pronouns), but semantically. This has been mentioned downthread, the original critique of these terms did not come from trans people, but ironically from radfems who opposed this default masculinity under a linguistic determinism angle, much moreso outside of the Anglosphere. For example, this is a major culture war issue in Germany, where reactionaries pretend that grammatically masculine terms, which are still commonly the default in German, are "gender neutral", whereas feminist and trans activists work on establishing actually gender neutral grammar as a new default.