I get the frustration that Dendrite dev has stalled, but the fault here is not of an evil take-over by Element (given Element wrote both Dendrite and Synapse in the first place) but simply neither Element and Matrix Foundation having the $ to do be able to maintain two homeservers simultaneously.

> Now the free and open source Matrix homeserver has to compete with a closed source commercial one

This isn't really the case - normal open source Synapse is the core focus for Element, and the vast majority of work is going into that, including performance work. Synapse Pro is "just" for scalability and HA for big government-scale deployments - https://element.io/blog/scaling-to-millions-of-users-require... etc. But all the schema work etc which supports that goes into FOSS Synapse.