Well zoomers are the gayest, most liberal generation yes, but they are also the most conservative and neo-nazi too apparently (probably a case of indoctrination and the counter-reaction to it).
This means that heterosexual zoomers are simply not on twitter, but instead are shitposting on fringe forums or busy fapping to animetits or instathots, watching youtubers and streamers all day or playing whatever fotm game, while normalfag and female zoomers are on instagram, tik-tok or whatever.
Twitter (and pokemon) instead attracted all the weird loser gay kids, sjws, fujos pretending to be sjws to not be accused of fetichizing homosexuals, normalfag attention-whore fags not much different from women and dumb npc-like girls that like being told what to think, oh yeah and all the "queer" faggots. Of course they are going to instantaneously flood the replies with gay shit, its their programming against such displays of relentless heterosexuality.
It's supposed to be for muh representation and visibility or whatever but it always felt more like resentment. In fujos case they are just loud and embarrassing.
Also shipping was always more of a fangirl thing, fanboys were always more self-insert types (well yurifags exist, but they are subhuman). That's why right now most of the heterosexual "shipping" you'll see comes from harem anime and gacha games, or /ss/.