You say that, but Element X (Android & iOS) already lacks full support for the oldschool way. It only supports certain flows therein AIUI.

Yeah, I realize that, but that's exactly why it's Element X and not Element. Element was actually planning on dropping support for older servers, but for ecosystem reasons they had to can that indefinitely. I don't think Element will become Element X anytime soon with the ecosystem in such bad shape.

Several years ago, Riot.im messenger had a branch called RiotX with some additional features. Then RiotX (or its codebase) became the first version of Element, while the original Riot.im stopped being supported. And this was when Synapse was the only server option and it was a hog for memory.