I presume anyone could've written a client for the frontend protocol -- I don't think I ever read that protocol draft. There was a general vibe that good frontends were an important problem and people would want a variety.

Yeah, it's questionable whether their business strategy could've evolved into a winning one even if they'd made it to launch.

I was just questioning the parent's perspective on "right libertarian ideology" -- my impression of Xanadu's vision was not so much "people love markets for information!" as "it's vital for the health of the info ecosystem that basic costs be paid directly", so e.g. the problem of UIs that people can rely on against scams should be faced and not avoided in favor of structurally leaning hard on advertising. (Yes, some kind of ads are inescapable.)

(It sounds like you've gotten to quiz MarkM on Xanadu directly; I'm going by largely-forgotten reading mostly in the last millennium.)

Yeah, but only last millennium. This millennium I've pretty much only talked with him in depth about security.