You say potato, I say "Parrot was designed to implement the semantics of both Perl 5 and Rakudo in the same process."
You say "It's better to build a specialized VM", I say "Emscripten, Clojure, Niecza, Truffle, and Jakudo."
You say "It's better to build a specialized VM", I say "Emscripten, Clojure, Niecza, Truffle, and Jakudo."
And as a counter-example, luajit2 was built by one man (mostly) over the course of a few years, and runs very efficiently indeed, in no small part due to the lua-specific choices that have been made.
So what I'm trying to say is that there is a second tradeoff, somewhere between programmer efficiency, runtime efficiency, and running time, and that MoarVM is making a better tradeoff for perl6 than parrot is.
Ha! My experience with Rakudo was "you go to the developer resources you have, tell them not to change anything, then tell them you're going to throw away their work in favor of something you haven't written yet" and then complain when they leave.