I recall that in about '92 Intel had launched a project called Eclipse which was an x86-based workstation they were developing to compete against Sun. As with many Intel projects, it didn't get anywhere.
x86 wasn't competitive on the server side until K8 (AMD) and Nehalem (Intel).
So you have a real long stretch -- 1987-ish to 2008-ish -- where proprietary UNIX on proprietary architectures owns the server side, even though the workstation market is eroding the whole time.
Google and Amazon launched world-beating datacenters before 2000 on P6's, that's just silly.