The DM uses their mic more than anyone else and may even have multiple groups. While it can happen, i mostly see it with new DMs and usually it isn't a big deal.
I do agree i see this more in players. It happens maybe every session but im usually quick to call a player on it if it's something like their turn in combat. Or a player was trying to roleplay with someone else's PC followed by a few seconds of silence.
For real. No one uses mics or even the text chat in games anymore—and when they do–it's because they don't realize that their mic is on, so all you hear is chewing sounds, the keyboard clicking, or the shittiest hip hop in the world at max volume. (Seriously, why is it never good hip hop?)
I miss the days when everyone was playing Valve games and the voice chat would be absolutely alive with the funniest people on planet earth. I miss all the memes, good music, and funny sound clips. TF2 right after the Heavy update (and Left 4 Dead) came out was peak multiplayer gaming. It's been downhill since.
Whenever anyone has been quiet for too long, I try to nudge them with "hey, if you've been speaking we can't hear you" - it's happened to me too many times already