Ring works on Android too, by the way, so mobile, for 70% of the world population is covered. If I remember right, it is not on iOS because Ring's license GPLv3 clashes with the App Store's license.
There are too a lot of chat clients, agreed. But that is the same as there are too many distros. Thank god for that, I say! The alternative seems to be one big blob of monopolistic, proprietary goo that invariably ends up devouring its users. If that is the case, long live fragmentation.