Of course. But understanding why calling women "females" is a big red flag is not about your intuitive grasp of the language. We dehumanise people by nounising their adjectives all the time. Are you epileptic, or an epileptic, or just a person with epilepsy?

It's harder to explain to someone with a poor grasp of English grammar, that's all. People who are fluent or near fluent because they grew up hearing and speaking a language will often struggle to explain something like this. People who had to learn the grammar consciously probably would not.

Only biologists and coppers need to use "female" as a noun. Everyone else can speak proper, like.