One can say terrible, one can say ingenious.
A news feed with comments and a group chat are projections of the same object, thus you have all the events in one "community" in one place, seeing them always (more or less, because going to comments of a post you only see that post's children and their children and so on).
Personally I think it's much more convenient than Discord.
And the public opinion seems to be in TG's favor for usability (except it exhausts me to see that many groups and checking them, so authors' FB clone background definitely shows).
I think the market has decided that this UX is good. But technically TG is, 1) proprietary in fact despite open client source, 2) insecure, 3) starts getting overloaded with features by now.
I'd want a federated FOSS alternative. I'm actually thinking how one can do that (especially the part about sharing files, the TG way means they'll have to be stored for long somewhere ; maybe one can have each user issue a fixed amount of tokens on registration, those tokens be passed by uploading user to the one providing storage, and somehow thus using local storage of users as a currency, for file storage only ; the thought is inspired by Redis and probably sucks, especially since in Redis tokens are for hash partitions ; it's also inspired by BitTorrent reputation and tracker ratings, where you have to upload something to be able to download yadda-yadda) without making running a server a very expensive task. Probably should read something on how XMPP and IRC and other server-server connections work, but lazy.
Interesting even, can a FOSS federated TG alternative be just another Lemmy frontend. Again, the attached files part should be solved in some smarter way than storing them all on servers, people upload huge things to TG. A builtin bittorrent client is not a solution, cause one person sharing a file and going offline means that nobody can download it. So the previous idea with tokens may be not too bad.