It's always been super popular, yeah! I think a lot of what I'm noticing is just some of that separation going away. Or maybe less optimistically the main separation in a lot of new fandoms is turning into pro-ship/anti-ship instead of ship/not ship or slash/het/gen and that's not as structurally obvious on AO3.

tbf "nobody reads gen" mostly came up in the context of "why didn't people like my genfic as much as my ship fic?" And the answer was really "your usual readers are shippers and *shippers* don't read gen." But AO3 leaves you a lot less dependent on finding readers in the same subcommunity as usual.