This is false. There is still plenty of metadata that centralized providers can capture and turn over and that is usually sufficient for law-enforcement to get the information they want.
Telegram used to be so darn satisfying to use years ago, but as soon as they started peddling a crypto"currency" it all went downhill. Deleted my account a month ago.
In my country it was never seen as anything else than a disinformation platform for Russian shills and rich "famous" people posting shit about invermicin and corona.
Sinal, Threema for security.
WhatsApp/Wechat for Family.
Telegram... for family you don't want but sadly have.
And where I am at, Telegram is just the main social network nowadays. VKontakte became unusable garbage even for an average person, Facebook never gained traction in the first place, Instagram and Tiktok are not that suitable for communities, Whatsapp is purely a messenger - and Telegram appeals to everyone, being a hybrid of a social media and messenger. So, while I was able to avoid Whatsapp, Telegram is actually hard to leave. Unuversity, art meetups, education channels - all there. I did get a few people to use encrypted messaging with me, but most don't care about privacy because Telegram is convenient and everyone is on there.