Normal app can do mayhem just as any app can, even Electron one. I do not use Telegram, and do not know about root access, and it should be investigated. But root access is not always needed for native apps.

Why is it better? Hundreds of reason, you can see down below. I will try to sum it up why I like native over electron in 3 words: responsiveness, robustness, cleanliness. Electron on desktop is resource hog for me. It is good for people that don't mind that, and that are deep into JS ecosystem. I am not, and I always prefer native app, partly because I am on macOS and Cocoa looks beautiful.