NT4 included all the supported architectures on the cd-rom. You didn't buy an x86 version or a PPC version or a MIPS version or an Alpha version... You just bought NT4 client or server and it was all there. Microsoft may have had analytics of use on ppc, but not specifically sales. OEM sales, sure.
More likely, no PPC oems were interested in selling NT5 (Windows 2000) bundled with their hardware, and so Microsoft gave up on that. Alpha was supported into the release candidates (and I've seen comments that builds continued but were no longer distributed outside Microsoft), but Alpha imploded during the release time frame.