The model of "contact us and we will arrange the partnership" was, IMO, very wise method of getting the ports everywhere. At one point this sparked rumours of NT/amiga due to some informal talks that never progressed anywhere, but with MS already having established a reputation of "you get an NT port, and you, and you!"

And MS actually went a bit further and enforced portability by developing NT on a non-x86 platform that nobody else had (IIRC using i860) and then porting it to target platforms - of which x86 was considered a bit of a toy.

This is heavily visible with how NT had to carry around a significant portion of ARC runtime so that its boot process could work on non-ARC x86.

Unfortunately, they didn't prepare well enough for 64bits, and we had to wait till Windows 2000 and Itanium port to get Win64.