Cuz they just tend to be slow. I don’t know how these apps behave on a 1500€ phone, but I had a pretty beefy computer at my disposal these last 2 years and web apps are just always slower, usually much slower.

And back to phones, the UI of graphics web apps rarely considers them. Or they simplify the UI to the point of being unusably dumb.

And Paint… Yes true, but again do you understand “phone”?