I love it, because I'm an engineer and know what all those buttons and sliders do. My friends? they didn't like it at all. Thus making the switchover even harder.
This issue has been mentioned in the past already, and I think Mumble devs acknowledged this in the past... having a well polished UI is so important for user adoption! Just throwing all technical choices to the user's face is rarely the right solution.
I used it with my friend in 2015 as a sort of galactic walkie-talkie on our phones -- he was in another country but we'd just walk around outside and talk to each other. It felt pretty futuristic at the time.
After a few minutes of continuous audio transmission though there would be a significant buildup of latency, so we developed the habit of saying "pineapple" to each other to measure the lag. Best record was 12 seconds.
Nice to see you had been having fun with it. Skype however had been there since a lot earlier, right? I guess that having to exolicitly "call" your friends removed a bit of that "walkie-talkie" feeling, but still...
Convincing everyone else involved to switch over to it however is a near-insurmountable battle.
Many years ago I was playing on a friends Minecraft server, while in a then Skype call with some friends on the server
One user couldn't get Skype to work on their Arch Linux install, and proceeded to spend almost an hour badgering us and whining to switch to Mumble so they could "join the fun"
From our perspective, shifting our entire group conversation over to a brand new voice chat system just for one person seemed like an absolute joke. So they were left wanting