I think that's actually a rather poor discussion, revolving around what is or isn't "ad-hominem", or which unimportant details of the history of WASM are inaccurate, or what the name of things should be.

All of the technical concerns raised by the post are either left unaddressed, or deferred to future extensions of WASM. In other words, the author must be correct in his analysis and the standard has made questionable trade-offs from the outset.

I can think of at least one reason why you might want a register machine: Not every platform is going to use or allow JIT, and a register machine would perform better here, i.e. like Dalvik in the early days of Android.