The only benefits I can see of "Apps", are the developer get's access to private information they really don't need.
Yeah, they get to be on the "App Store". But the "App Store" is a totally unnecessary concept introduced by Apple/Google so they could scrape a huge percentage in sales.
Web browsers have good (not perfect) sandboxing, costs no fees to "submit" and are accessible to everyone on every phone.
Just to confirm:
I dumped all of my notes from my insanely large apple notes (about 16000 lines of text) and pasted them into Google Keep, Notion, Google Docs. With the exception of Google Docs the rest of them flat out froze and I had to kill my browser. Stop trying to tell us that the browser is the answer to everything when most web apps cant do the job of Notepad.exe or vi
Tried putting 20k lines into it. Loaded instantly, allowed me to scroll and edit flawlessly.
But I get your point. I'm on a pretty decent 2022 iPhone, and I'm sure at some stage I would run into a performance hit. But not at 20k lines.