Matrix is an open protocol published by a non-profit foundation. It has always had both FOSS (eg Element) and proprietary (eg Beeper) implementations.

You sound like you are getting Element mixed up with Matrix. Element releases almost all of its implementations as FOSS, and to help Matrix grow, will make those as good as possible for average server sizes. It’s only gigantic servers which actually require the new proprietary modules. Given everyone who uses FOSS Synapse can keep doing so, and given FOSS Synapse dev should hopefully improve and accelerate if actually funded by $ from Synapse Pro, it’s not fair to say that “FOSS is essentially a marketing tool for Element”

Isn’t that true for most/all corporate FOSS projects? I don’t think there are many for-profit companies who have some kind of idealistic vision of FOSS. It’s always part of the business model. Would be weird otherwise.