We often hear that "Hypergamy has no ceiling", but you can only inflate your expectations so much before reality sets in. I'd say that "Femcels" are a good example of toilets with standards so high that they unironically become Incels because no man can match their fantasy mate.
If every toilet wants a 6'9 Millionaire with perfect abs, blue eyes, and a giant shlong than the few hundred men in her country will have to find a way to sleep with millions of toilets. Chadopolies function based on the best Chad that local toilets can realistically get. If Hypergamy rises without the supply of these supermen also rising then you'll just get more disappointed toilets.
As for height, I live in the Netherlands, only 30% of men are shorter than 6 foot here. I see toilets with shorter boyfriends every day, often I see Stacies with men shorter than them because the moment tall men become the norm it's no longer something special. I was in Amsterdam and I was just looking at crowds, men that would be considered "giants that tower over others" simply disappear in the crowd here, unless you're an ultra rare basketball player who's even tall for a basketball player no height stands out in the crowd here, even 6'8, 6'9 guys don't look like anything special in crowds (here). So other things like jawline become more important. In a place where height is abundant height becomes irrelevant. This is probably also why it's so common to see tall White Dutchtoilets with short Asian men in the Netherlands.
As for why standards are rising, it's simple, a toilet with realistic standards will easily find a mate, she will find what she likes and settles down. The toilets that are "left behind" on the dating market are there because their Hypergamy isn't realistic for what they can actually get and they get resentful and bitter. This is one of the reasons why standards are rising, it is because the toilets that actually aren't as demanding are quickly taken out of the dating pool.
So the longer you're single, the more you have to deal with shitty entitled toilets that have nothing to offer and everything to demand.