This is dreadful. The Free software movement has existed for decades and Telegram brings nothing new to the table that Google hadn't already a decade ago (open yet crippled protocol, proprietary servers). There is nothing new here, besides the fact that Telegram basically makes no money. Which is also nothing new, since Google Talk and Voice never made money either!
I don't mind it, because we know the protocol and can reengineer the clients easily in the event they betray their users trust. It is much better than WhatsApp or Skype being a whole-pipe black box. But at the end of the day, XMPP has existed, has improved, and today provides all the features of all these other messaging transports and more, the problem is there is no money to be had in providing an easy signup XMPP service, so nobody advertises them. Which makes Telegram perplexing, because their only valuable resource is their userbase, and they are not directly monetizing it at all. Contrast that with Duckduckgo having an XMPP server @dukgo.com that basically got a blog post and hasn't been talked about much since, that I use all the time on all my devices.
But fundamentally none of this absolves how stupid all these companies re-implement a wheel poorly (XMPP) because the old wheel is so well known and understood that you can't lock people in or profit off the users using it.