Google Hangouts on MacBook Air

Used Google Hangouts with multiple (three) users with 2 MacBook Air (MBA) and 1 MacBook Pro (MBP) tonight. This was my first time to use Hangouts with more than two persons.
While we've already found it is too heavy to use video on MBA and MBP both and turned off the video feature this time as usual, it was still uncomfortable since the volume was different person by person. Can't ask one to change the input volume setting (microphone) while the online meeting. One idea to solve such a problem can be a implementation of volume mixer for each participant in Hangout.
By the way, while I remember everyone used Skype's video chat several years ago, why do they use Google Hangouts now? That's my question of the day.
Still can't imagine what I will use for online chatting/meeting in 2017.