I guess they figure they are better off with the revenue from an OEM license than no revenue at all
I think overall there does need to be a better push by Microsoft to clarify to Joe Bloggs in plain english what OEM means. And anyone selling to Joe Bloggs types should really require J.B. to pick up the phone and be told all about OEM software rather than just being able to order it off the website.
But yes, I guess it probably is a case of revenue from mischanneling vs no revenue from pure piracy.
Being a Mac user outside of work, I'm not one to defend Microsoft ...however I do think that the discount given on OEM products in return for stricter licensing terms is a fair one, and that the OEM licensing terms themselves are also pretty fair. I'm all for "home" system builders .... I've built one or two PCs myself, back in the dark ages .... but if licensing terms are abused, you may find Microsoft only making OEM available to branded PC manufacturers ....
I think my 2p worth has now become £2 worth ..... so I'll stop here !
Best of luck with your home PC building antic .... great fun ! Wish I still had the time to do that !