I kinf of fear the reason Purism went the way they did is because their background is in desktop, not mobile. And if a company has strong NIH culture they'll not easily fold and go the SFOS way for example; instead they will use the only hammer they know to the mobile UI which they see as another nail...

Mind you they got the low layer right; they have upstreamable kernel and drivers. I only wish they'd taken Nemo as the middleware layer