I was on Wattpad years ago and my conclusions are based on that experience. I posted my entire first novel to get a wider range of feedback and all I got was blind praise, and most of what I was for other stories was the same. When real criticism was offered it was dismissed. I can only assume it's gotten even worse. It was not only romance. There was a lot of scifi, mysteries, horror, fantasy, and every other genre. Mostly fan fiction. I didn't read every story, but even among the few written by people who genuinely wanted to be writers, I saw nothing ready for self publishing let alone good enough to be picked up by a publisher (although I admit publishers look for what's marketable regardless of quality). To me it was a mostly another bunch of people seeking reward without effort while ruining it for those seeking to better their writing.
Well, I'm not sure when it was that you last tried it but right now it's pretty heavily leaned towards romance. Even the Wattpad-published books you have to pay for are mostly romance. Most of the fantasy stories are supernatural/paranormal romance, or urban fantasy with... lots of romance. Some of the top titles: Bad Boy (ooo la la). Jack the Panty Ripper (lol?).
Of course, it's not everything as I said. There are a few traditional fantasy stories that do well there and stuff like thrillers. Some webs serials and litrpg stuff too.
In general though, Wattpad is still mostly young adults/teenagers and majority female I'd guess. Compare this to, say, Royal Road that is almost majority teenage male with a hard lean on fantasy, wuxia, and litrpg with a dash of sci-fi. Technically it's mostly "romance" too if I dare call it that, but the horny teenage variety... most stories usually involve ridiculously powerful heroes effectively collecting girls on their way to glory and fame. Big enough that the harem trope is... well, a harem trope.
Again, not all of them. There's tons of good regular fantasy/sci-fi there too and some female authors too, but you can kind of tell the primary demographic of these sites pretty easily by what's popular.
Scribblehub... top trending novel right now has an anime cover and is about a guy who dies and is reincarnated as a succubus and promises at a lot of sex. Read the warning about how there's a lot of fondling and pining between underage lovers, but no actual sex, and try not to get a headache. Oh, and that's without the author pointing out that everyone in the world is older than they seem... and that the MC is technically even older because he's "reborn."
This all with a lazy Google of sites similar to Wattpad! Hah.
But eh... romance and erotica/harem are hit with teens/YA these days I guess.