It took slightly longer than expected for me to track down an explanation of their business model. I think it boils down to "run cheap until we have one".
https://developers.revolt.chat/faq/monetisation
By making their backend AGPL they've left themselves a path to some kind of profitability for companies that want to run custom versions.
They're running Docusaurus for docs but adding manual timestamps instead of using the built-in showLastUpdateTime variable... this hurts me.