Perception, PR value and integration. I (for one) am in the trenches. Every day I try to convince companies to use the block chain for application building. I had (still have) a hard time convincing people to do this, even with (because of) all the negative connotations (abuse, crime, etc.). Once MS started supporting this, my job became a whole lot easier. There was immediate perceived value. But that probably only works if the potential customer has/runs MS products. This would not make much sense to an outsider (i.e. a customer who doesn't use MS products).

EDIT: Partnership is probably not the correct term. More like cross promotion, you are listed as a "Value Added Solutions Provider" (or something like it)