This sharing creates new abstraction boundaries, increases the number of concepts and moving parts, and there are lots of compromises involved in reusing a common part compared with crafting something small and simple specific to the task at hand. But if you didn't do this, you'd have lots of duplication of similar, but not quite identical work, like a pre-industrial society; a massively inefficient use of human labour.
You can't pause the world while you rebuild everything; it would take far too long to get to something better than what you're trying to replace. You can only repair one or two things at a time, and hopefully leave the world better for it; but the mindset espoused in the rant is more likely to result in a half-baked start on something new, but abandoned when the scope of the whole problem is fully perceived.
Just about everybody knows that all our software is imperfect crap on top of imperfect crap, from top to bottom. Everybody, when met with a new codebase above a certain size, thinks they could do better if they started over and did it "properly this time". Everybody can look at a simple thing like a submit form in a web browser, and sigh at the inefficiencies in the whole stack of getting what they type at the keyboard onto the wire in TCP frames, the massive amount of work and edifices of enormous complexity putting together the tooling and build systems and source control and global coordination of teams and the whole lot of it, soup to nuts, into a working system to do the most trivial of work.
But this is not a new or interesting realization by any means. It's not hard to point almost anywhere in the system and think up better ways of doing it. Pointing it out without some prescription for fixing it is idle; and suggesting that it will be fixed by wholesale replacement by another complex system is, IMO, fantasy.
Unless the new thing isn't Turing-complete and can't be implemented with a Turing-complete system, it will be abstracted away at first just so we have an environment to start building with, and can start using it without reinventing every single wheel we have.
Without radically changing the paradigms on such a fundamental level a start-over just wouldn't happen.
I don't think Ryan Dahl is at all naive for wanting something like this. I also think something like this is totally possible.