Websites, at least on iOS (not sure on Android) can't receive notifications in the background or GPS pings the background and therefore can't notify you 'warning: police 100 meters ahead' while you use the phone for other things like an app can.
This argument has been waging since the app store was first introduced. For games/graphics intensive applications, sure an app is fine. Everything else displaying some text, the web should be standard.
There isn't really, you can hit 60fps on both, especially on current iPhones. The main thing missing on the web is an equivalent to Metal (they are working on it) so it is not possible to built 3D apps without sacrificing a lot of performance.
It really hard to get an app-like experience in iOS Safari. I don't know if they intentionally cripple it, but they certainly have no incentive to make it good.
Russia has been trying to block Telegram for a few years no, with no success.