Skype, Google Hangouts, teamspeak, ventrillo, mumble, and tox all support my microphone and voice activation correctly.
Its even more useful in competitive gaming and/or streaming where many want to chose what to say to their team/friends and themselves/the stream.
(can you tell I’ve played Overwatch?)
That said, I use a for-realsies dynamic microphone with tons of off-axis rejection and a wall-mounted arm (I play games in my office/recording space, that's the engineer station mic). So I probably could use voice detection and be fine. But habits die hard.
The rise of mechanical keyboards has made PTT practically the only option. Otherwise you just hear little clicking all the time.
