I worked on a project mid-aughts to port a scientific package to Itanium. The issue that we observed was that Itanium really pushed the hard work out to the com

I worked on a project mid-aughts to port a scientific package to Itanium. The issue that we observed was that Itanium really pushed the hard work out to the compiler and by association the devs to make everything work with their compilers in order to get the full benefits. And since very few people had Itaniums and the compilers weren't quite there yet, the overall dev effort was not worth it. Somewhat of a chicken and egg problem. ARM managed to be worth the trouble since it solved a real problem of power useage which got it the installed base, at which point it was worth the trouble of supporting.