Pretty good explanation of evolution; too bad they logical fallacy that into applying to modern human relationships on a microlevel. (In the first place, evolution applies to communities, not individuals...) Like, if "being ugly" was as detrimental as she's making it out to be, (such that those who are are "doomed to a life where they can never get a girlfriend") then it would have been selected against already. The previous generation of "ugly people" wouldn't have had children, and so there wouldn't be any ugly people this generation, (Unless she's implying that Homo sapiens is undergoing a paradigm shift right now?) and the same applies for that previous generation. The generation before that would have weeded out its own "ugly" genes, which would have actually been weeded out the generation before, which would have... &c.
The fact is that next to no one actually exists who is so naturally "ugly" that they cannot find a partner. (This is of course not counting people who have become disfigured in accidents or otherwise become less visually appealing later in life.) Sure, finding one is easier for some people than it is for others. But the people who think that they can never find someone are just... wrong, at least when it comes to inherent biological reasons. If you really find it impossible to find a girlfriend or a boyfriend, that almost certainly is due to something other than your genes. (Your personality? Your way of life? Your interpersonal skills? Your lack of self-care?) And even if there is something biological, appearance is absolutely one of the least likely for that to be, as it's extremely easy to select against. It's next to impossible for someone to have a child before "the fact that they are indescribably ugly" is revealed to their partner. It's not like you're a carrier of some hereditary disease or anything.
And that's something she could have explained instead of the whole "yeah, it's impossible, y'gotta fake it" and I don't think it would have really negatively effected the manga very much. (Oh, but the fake dating plot would have felt contrived! Woe!) And, honestly, what they did go for feels uncomfortably similar to what real, self-identifying incels believe, that the only way to be popular is to "fake being more masculine" and that the world is against them and it's not their fault at all.
Like, I've been single my whole life, but I'm not going to pretend that's biology's fault! My parents had children, my grandparents had children, my great grandparents had children, my great great grandparents had children, &c.; I'm clearly of a lineage that's pretty good at finding mates. I'm just shit at talking to people and don't really care enough to work on it. So if you care, then own up to your own faults and work on yourself! Don't blame the genes that have persisted across hundreds of generations.
Which is basically the same message she goes for at the end but with a different nuance, I guess. But MAN it has got to be faking or else we can't do a fake dating plot, huh???