Humans are all biological but there is an important distinction between sex and gender that i refuse to conflate, as that would be pseudoscientific. Both contribute to what is considered male/female, but one is biological/sexual, and the other is social/cultural. and yes, transwomen can be considered biological woman as well, although this cannot be an exact term, just like gender isnt. So you will never be able to say a person is exclusively one or the other. its just that some aspects of who they are are definitely biological, and some definitely arent. This is not made up. Also the sex you are identified as you are born is not the only factor for treatment. Physicians will definitelly want to know your hormone configuration has been changed because it affects body function in many ways, ultimately changing your sex.

Straight and gay people still feel atracted to those with specific sexual traits, whether natural or artificially developed, so the description is still important for dating. Some people dont care much about gender, but still consider sex important. And of course physicians are rarely interested in gender either when diagnosing medical conditions. What concerns them is biology. So just because transphobes misuse terms to justify discrimination, that doesnt render those terms invalid.