Telegram is also the best at first class support of all the platforms it runs on. In addition to the Qt-based app that's popular on Windows and Linux, the predominant client on macOS/iOS is AppKit/UIKit-based, and there exist numerous other native clients (such as UWP/WinAppSDK on Windows, GTK on Linux, and CLI for anything with a command line).

In comparison everything else puts reasonable effort into the mobile clients and phones in the rest with bloated, half-baked web apps or if you're lucky an iOS Catalyst port.

Along with UI/UX quality, this stuff matters and impacts adoption, even if most users can't put their reasoning into words.