Sure you can, but then who will diagnose and fix your hardware/OS interaction problems when you have parts from five vendors in the mix?
If you haven't lived through this, the answer is: nobody. Everyone points fingers at the other 4 and ignore your calls.
Back in the day you could buy a fully integrated system (from CPU to hardware to OS) from Sun or SGI or HP and you had a single company to answer all the calls, so it was much better. Today you can't really get this level of integration and support anymore.
(Actually, you probably can from IBM, which is why they're still around. But I have no experience in the IBM universe.)
This is why Oxide is so exciting to me. I hope I can be in a company that becomes a customer at some point.