You have to understand that years of reading shitty Heisei-era romantic comedies have warped the perceptions of the average manga reader. The constant fake-outs from mangaka like Komi, Miyajima, Haruba, and of course the progenitor Akamatsu have made readers angry because they were expecting a payoff that was never returned to them - ignoring the fact that they’re Shonen romcoms that were aiming for maximum conflict so that they could run for as long as they need.
Hence why now, if a romantic manga doesn’t have the main characters immediately get in a relationship and have penis-in-pagina action within the first volume, people get mad. They want an immediate romantic couple with minimal-to-no conflict at all, and then are surprised when so few authors can do that well.
Welcome to Reiwa, though it's more about the departure from pre-relationship drama, and on to more dating drama, than just "on to sex". Sex can obviously play a role in it, but it's not integral.
Most of the ones you mentioned do have the " payoff " mentioned, though Haruba had to "fix" it with the movie, and Miyajima deserves an award for Most-Milked series (read as Most Needlessly Drawn Out). But I don't disagree with the conditioning, only the characterization of Reiwa era equaling a jump to sex.
I think its more there's a large demographic of readers who want "couples" to connect physically, in order to feel satisfied. There's too many potential reasons for that so I won't even try. It's an organic shift from spending a series on edge for a couple to confess/get together. With that milestone taken care of, they find themselves a new "goal". I guess it depends on whether or not you enjoy the more realistic SOL aspects of a romance.