Yep, it started as a chat system for gamers. And while that may still be it's primary userbase it has also become very common for online communities to text chat, voice chat, and hang out. Many online forums and communities have a discord server too (and many set up a gateway between the their online forum and the chat server). People often run the app on their phone and just add bits to convos when then can.
I did find a discord server for drone pilots, but I would have thought there were more. I just got on the one I found recently - so not enough experience with that group yet to see the level of expertise, etc. but will advise.
No thanks. There's already multiple forums, 5 different facebook groups, and a gitter channel. Adding yet another social media platform to discuss the same thing is going to hurt more than help at this point IMO.