A torrent remote app would never be allowed on the IOS app store, but going to https://remote.vuze.com and pairing your Vuze app can't be banned....
It's also unfortunate that web pages have the disadvantage that they have the browser UI around them, so it reduces the space available to the page versus an app, and web pages don't have permissions that apps do like sending notifications. Some people view this as a good thing and I tend to agree, but it's still a big disconnect that my weather app can send me a notification saying there is a tornado in my area whereas a weather website needs me to actively be checking it.
On iOS, this is literally a two-tap process (share sheet -> add to home screen). I can't speak for the masses, but the reason I don't do it more often is because so many web apps are just bad on mobile. Slow, poor rendering, no attention paid to extended usability...
When you visit a proper PWA multiple times, your browser is supposed to notice and ask you if you want to save it to the Homescreen.
But you're right, web on mobile is still miserable in general.
I just pinned a few sites I use.