Because straight men have vagina fetish, which they need to unlearn.

I don't know if you're old enough to remember when Eddie Murphy got caught with a transsexual prostitute:

https://archive.is/Ynfbs

(Everyone should take a gander of how this stuff used to be reported back in the day. All he/him pronouns, no fucking around with gender nonsense.)

Anyway, when these stories came out, people flailed around trying to figure out what to call these men. Were they gay because they liked sexual partners who have dicks, or were they straight because a hole is a hole and a hole wearing a dress is almost like a woman, so who cares? (This is not me saying this, this was the general sentiment. Like, there was a difference between fucking a man in a man costume, and fucking a man in a woman costume, the latter was significantly less gay, for some reason, but in this article, the writer seems to be of the opinion that it's equally gay.) And no one ever said... What about bisexual? It's like that wasn't even an option. These two men were either gay or straight, but definitely not bi. What is bi? That doesn't exist.

So anyway, back to what you're saying, it occurs to me that the people saying this stuff forget that tops and versatiles exist. I can understand the leap in logic, to think that wishing to be penetrated = woman, but how about wishing to be the penetrator of men? How does that = woman? And what about the gay men who don't want to have penetrative sex?

This theory smells like another one that's been cooked up by clueless toddlers who have no idea what they are talking about.