Strategically it makes sense. Apple is a hardware company, so making it difficult to run their OS in the cloud means more people need to keep buying their hardware. Microsoft has their own cloud, where they don't have to deal with the license requirements they force on other cloud providers, which gives them a competitive advantage over their competitors (when it comes to windows servers). The key is that these companies don't just sell operating systems. Red Hat on the other hand, which doesn't have competing market pressures, is much more friendly to licensing in a cloud environment.