That is an odd article. It says they would prefer a federated messenger like Matrix and then lists all the problems with it, while totally ignoring XMPP/Conversations in the entire article, which has long solved all the problems mentioned about Matrix…
Some people really have some serious blind-spot issues when it comes to XMPP.
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The Conversations client defaults to e2ee (and it is trivial to setup on your own server, works by default) and there are plenty of free, community hosted servers to use.