It would be cool for clients and protocols to be separated by an abstraction layer, it might change the n times m to n plus m but I suppose it's difficult
Pidgin implemented support for various networks under an abstraction layer and had a unified UI for all of them.
XMPP implements this via gateways. I used to talk from XMPP with folks who used MSN or Yahoo on their end. We have gateways for Telegram, WhatsApp and Signal nowadays.
The Nokia N900 used the Telepathy framework to expose a local D-Bus messaging service which itself connected to various networks (SMS, MSN, XMPP, etc). The UI was a single unified one for all these networks.
