In France, SMS is still the most common, even though it is declining. I think it is historic: we had cheap unlimited SMS plans before internet data plans were common.
WhatsApp is popular but not a monopoly. Not really something to celebrate since its main "competitor" and #1 instant messenger app is Facebook Messenger. Skype and Discord are also significant, and I expect iMessage to be important too.
Based on all the groups my wife is part of, it seems other people get absolutely nothing done in life since they appear to be sending pointless messages on a group constantly. Her phone is constantly buzzing, and 99.9% of it is utter nonsense.
It seems to me that the inability to easily message a group would be a bonus and not a loss!
