I bought mine a looong, long time ago (ended up with the Mariko model which required some, ahem... tweaks, hadware-wise) for Fire Emblem: Three Houses and Super Mario Party. Ended up also loving Animal Crossing of course, but nowadays I use my Switch almost exclusively for Otome games and it is, by far, my favorite platform (second only to the PSVita, handheld is so much better than Switch) to play them on. (˶ᵔ ᵕ ᵔ˶) ‹𝟹
I also considered getting a Steam Deck because honestly I just really, really hate sitting at my desk and reading.
As for why there are so many, I'd wager that it's because the Switch is the current successor to the Vita as far as visual novel/otome gaming goes. It's the most widespread handheld at the moment, people clearly love it (perhaps not the prices, though that's neither here nor there), and so publishers keep making games. Also, it's probably not that difficult to port visual novel games in general. There aren't such a wide variety of different assets as in, say, an MMO. (*ᵕᴗᵕ)⁾⁾