The reason for that, is to avoid having influence from outside. Even "angel" investment can be problematic, as the "angel" has the ear of the leadership.
I have found that even well-meaning outsiders can have highly destructive influence, because they don't understand the culture and they aren't the ones on the hook, if things go pear-shaped, as opposed to the ones that have a real, personal, stake (like all those Ello users, who lost so much).
I'm just thankful that mobile phone networks haven't switched to a "free with ads interspersed into your texts" model yet.
(Of course there are still ads in my texts, but at least those are officially spam rather than network endorsed.)
Literally in a span of months SMS usage went the way of the dinosaur.