>> In a nutshell, this is considered a turning point because Telegram's official stance is (even today) that they don't share data, not even with any government.

If you care about your privacy the "official stance" alone is close to worthless. That includes governments and corporations as well. I think we already learned that. Just like on security you need in defense in depth on privacy(i.e. hardware, software, and "official policy" as well).