I think that statement suffers from hindsight bias: x86 is great now because of enormous leaps in compiler technology to work. Yes, compilers do need to evolve with CPUs, they don't just grow on trees!
Put another way: given a choice between stuffing an electric engine in a Ford Fiesta, and a Tesla, Itanium could have been the Tesla in the hands of another company, but the market went after the Fiesta retrofit because it was here-and-now, not coming-soon.
EDIT: changed from "you" to "that statement"; added analogy.
I don't believe that's historically accurate at all. x86 compiler performance has been good enough for a long, long time. Yes, newer versions are clearly a lot better than ones from the mid 90s, but the performance improvements would be described in terms of percentages, not orders of magnitude.
IA-64 required a complete rethinking of compiler design to solve NP-hard problems on a large scale just to get passable performance. Translating C to ASM that keeps execution units busy is radically different on IA-64 than pretty much anything else.
Put another way: given a choice between stuffing an electric engine in a Ford Fiesta, and a Tesla, Itanium could have been the Tesla in the hands of another company, but the market went after the Fiesta retrofit because it was here-and-now, not coming-soon.
EDIT: changed from "you" to "that statement"; added analogy.