So if the motherboard is spoilt due to lightning strike or whatsoever, user would have to purchase another OEM or retail OS for their new motherboard? It makes sense as this is one thing that makes it different from retail version, I wanted one due to its low price but not anymore as it's not transferable.

I think re-activation is more for those who reformat their PC but from what I heard it seems the rule bended in a way that hardware changes are applicable through sweet talking .