From skimming the link above, it seems like they accepted it's extremely difficult (maybe impossible) to generate high ILP from a VLIW compiler on complex hardware (what Itanium tried to do).

So they attacked the italicized portion and simplified the hardware. Mostly by eliminating memory-layer non-determinism / using time-sync'd global memory instructions as part of the ISA(?).

This apparently reduced the difficulty of the compiler problem to something manageable (but no doubt still "fun")... and voila, performance.

The problem set groq is restricted to (known size tensor manipulation) lends itself to much easier solutions than full blown ILP. The general problem of compiling arbitrary Turing complete algorithms to the arch is NP hard. Tensor manipulation... That's a different story.