XMPP was developed as an open protocol to bridge to proprietary communication platforms, just as Matrix is today. There are still such bridges (more commonly c

XMPP was developed as an open protocol to bridge to proprietary communication platforms, just as Matrix is today. There are still such bridges (more commonly called "gateways" or "transports" in XMPP), such as for WhatsApp, Signal, and others. However my perception is that over the long period of time XMPP has been around, focus shifted to the "native" XMPP-XMPP use-case, because it's easier to build a better experience that way. My personal prediction is that Matrix will certainly go the same way - using a focus on bridging to bootstrap the network in the initial years, and then gradually shifting to focus on "native Matrix" for most use-cases after reaching a certain critical mass.