I don't know why a lot of places don't have a gallery view, it kinda turns me away from them immediately

Exactly.

IIRC it's not even a hard thing to implement, code wise.

Another thing that kinda bugs me about Twitter being so popular for artists is that Twitter only shows the most recent 3,200 tweets (if you can even scroll that far)

Right, it encourages artists to retweet the same 4 images constantly.

Yeah, it can get annoying, but it's a bit sad that there isn't any other good alternative that is popular enough for people to stick with, but it seems like a lot of artist are switching to Pillowfort, so hopefully with some updates, they'll add a lot of quality of life things for artists like the gallery scroll feature.