In any case, given the huge upfront investment required for a quality platform this doesn't seem like something an edtech startup can bootstrap. An education platform is not a CMS and its not a social media platform. I think especially now with the pandemic experience it has become very clear how rich, complicated and demanding the educational process actually is. The "archaic UI and features" comment hints maybe at too narrow and technical view. It may be a very relevant aspect (eg if young students puke at the UX it is not of much help). But from an education perspective what matters are not smooth appearances and gimmicks but "educational outcomes".
If you dive into the Dougiamas/Moodle team's thinking you'd see what permeates the design/architecture is to be able to translate the huge body of educator experience and infuse it into software. Somehow we need to move to the next chapter of the book they started writing.