I manage a Discord server for a few friends, topics are gaming related (DCS World primarily, but also Star Citizen and iRacing) - could easily be other hobbies.
I have structured the channels to support the learning journey that DCS is.
I absolutely love it, so incredibly useful. It's very easy to share resources, pictures - anything. The voice chat is also superb, just hop into a fixed hangout channel that anyone can join. I'll often just go into one early in the night, so that my friends (all over the world) can see me and hop on if they want.
I have joined server vendor specific discord servers, as well as racing league ones. The fact that they are invitation based is perfect.
Furthermore the scan on screen QR code with phone to sign in on desktop merits special mention, another massive usability win.
I specifically love how siloed it is or can be. Sure there is a lot of fluff they're putting in (game stuff in the message editor etc) which I just ignore; I can only hope they never change this core design and turn it into way more than it is now.
(Have been using it heavily since 2020, but started before then - fwiw. It absolutely helped me get through some of the strictest lock downs in the western world. Oh and I'm in my fifties, been on computers since the Vic20. I pay for Premium, and also for my early teenage son who uses it with his friends).