I would imagine those people are conflating “asexuality” with “person who is not asexual but experiencing a lack of libido from something like an ssri”. These are distinct, obviously, and the latter can be treated. It is also generally easy to identify

But just like so many things stupid assholes will go “I cannot conceive of a life without ‘x’ so when you say you have a life without ‘x’ I will assume you are either lying or mistaken somehow”.