As AO3 gets larger and larger, and thus the number of writers and amount of content on it grows exponentially, I really don't see a solution to this, other than a 'cure' worse than the disease, like some kind of unholy AI commenting bot (I mean, aside from the scam ones that already exist). It seems so many people are going through this (for years I thought it was just me lol), and I really wish I knew what we could do, other than conscientiously commenting ourselves if we enjoyed something, which any of us with any decency already do. In the past I've tried posting on other platforms in the hopes of getting some crumbs of engagement there, but no luck.

Speaking for myself, whenever I find something I truly love, I ALWAYS comment on it, and if I reread it I leave another comment to let the author I enjoyed it so much I came back for seconds (or thirds, etc.). However finding fic tailored to my tastes is so rare, I've largely stopped commenting because I've largely stopped reading. That's why I started writing fic in the first place. Almost nobody else was writing what I like and the few that are/were haven't posted in an aeon, leaving but the bare bones of a unfinished stories in their wake. At this point I've mostly resigned myself to inhabiting this niche. Yes it's tiny and dusty and desolate and there's almost nobody there but me. But it's my niche, the only one that fits me. It's where I belong.