Facebook is also filled with great features, but since they're not private we don't really consider those features but tasty baits for stealing our personal data. The question is, why should Telegram whose author is literally called the Mark Zuckerberg of Russia, be exempt and handed all that data. Of course he wants to make the app that gives him all that valuable data easy and fun to use. The real engineering starts when you want to achieve those fun features in a secure way -- people should ask WHY is it that it takes a bit of time from Signal developers to implement same features. That's precisely why. They're actual features with painstaking security design with clear rationale and security proofs, not a dish of spyware served with the side plate of bullshit that is damage control.
I guess it's because Durov attended the St. Petersburg military academy and studied propaganda and information warfware that makes him such a chef when it comes to the latter.