The whole point of XMPP or Matrix is to provide interoperability between IM services. For interoperability to exist, we must agree on standards. Matrix is not a standard, but essentially a product controlled entirely by NewVector, a venture capital funded start-up.

They are not profitable and increasingly desperate to make money. Recently they forked Element and Synapse and make contributors sign a CLA which enables them to change their software to a non-free license in the future for monetization: https://drewdevault.com/2018/10/05/Dont-sign-a-CLA.html

You might say "But they made a non-profit foundation for Matrix" which is kind of true, but not really. The "core spec team" is all people working for NewVector except a single guy. Go checkout their linked GitHub profiles.

The whole Matrix thing should build on the existing XMPP internet standard. Instead we got yet another incompatible IM protocol, effectively controlled by a single corporation and more fragmentation. Bridges don't help as they break almost all features, most regrettably end-to-end encryption. We really need proper internet standards for interoperability.

XMPP is also more lightweight and has proper native clients for all platforms instead of Electron apps. On the server side the difference is even more severe.