I don't know the exact reason, but all empirical evidence shows that it does. E.g. the whole of Europe still using Microsoft because they can, even though bits and pieces get cut off (like the ICC). If Microsoft cut off the whole of Europe, then Microsoft wouldn't have power over them any more.

Microsoft's days in many EU countries' government departments are numbered regardless of what Microsoft does. The understanding is there: a critical dependence on a product coming from a now-unreliable ally is a problem. It will, however, take many years for this to actually happen, because it's much easier said than done.