I think the idea there is that it's less direct. Intel's lack of interest in a 64-bit x86 spawned AMD x64. The failure of Itanium then let that Linux/AMD x64 kill off the workstation market, and the larger RISC/Unix market. Linux on 32 bit X86 or 64 bit RISC alone was making some headway there, but the Linux/x64 combo is what enabled the full kill off.