I think it's more about scale. Mumble and co. have good enough noise cancelling and management options that it's reasonable to have 30+ people in the same chann

I think it's more about scale. Mumble and co. have good enough noise cancelling and management options that it's reasonable to have 30+ people in the same channel. Skype becomes a mess around 4-5 people. Discord is still much worse than Mumble, but apparently still close enough that people can't be bothered to set anything else up.