itch.io is a small little fledgling website that has only existed for a few years -- i'm gonna say about two or three? -- and jumping into the current gaming ecosystem, which is currently dominated by Steam and GOG of the like, and finding any kind of significant visibility is a real tough thing to do!
i remember this being a problem for me when i first started releasing stuff (way back before i worked here :B); it's real hard to get people to look at your stuff just from posting it here. most "gamers" don't really care about itch.io, and it occasionally gets a bad rep in hardcore gaming communities because our catalog of available games is so completely out there compared to other marketplaces, and we allow all sorts of experimental work, which most gamers, despite saying they want new stuff, don't seem to actually want very much.
of course, this is a thing that shouldn't be considered a negative, in my opinion, but that's how people feel! we're "too new" and our catalog is too weird and diverse. we also don't have a functioning app like Steam yet, although we have one that Amos has been working on for a few months now that's shaping up really well! i personally feel the app will go a decent way towards getting more eyes on itch.io, since a lot of people find the convenience in automatically downloading updates through an app a necessity. we've also been doing a lot for the site to keep growing it, and it does seem to be working pretty well; a year or two ago, we would have never had a big enough community to launch forums!
i think that one of these days itch.io will become a lot more popular as it offers many benefits not just for devs, but for players who are looking for new experiences. until then though, us devs still have to be our own PR; we have to hit up websites that write about and do video for games and try to get our work in peoples' hands so they'll support us! as itch.io, we can only do so much at a time to get the new work out there right now.