I don't claim it has good UX. I claim it has good semantics.

The one you mentioned for starters - following multiple channels in a single feed.

I didn't mention that.

But I also think having everything in a single feed from all places would really suck, like it does in FB.

Telegram has a terrible UX for social networking and feed following

What social networking is has many different meanings, easily creating groups (communities) and posting\commenting there, like in LJ, seems more important for me.

it’s a private messaging app

It's not.

that has been hacked together into use case it was never made for in the first place and it really shows.

Factually wrong - it was from the beginning intended to be what it is now. Channels and chats.

And, of course, I don't think your ideas for that use case are better than Telegram's. I don't think social networks with feeds and following are something good.