If you're in a large corporation, it might not be that easy. I've been at multiple companies that have left AWS due to the fact that Amazon has in other lines of business been a competitor. So we're locked in for reasons that are completely unrelated to technology. It would be so much better if AWS spun off into it's own company.
define easily! if people go all in on Azure they become very deeply entrenched. Granted it is usually something that could be migrated from, but not without a significant cost if you already have a lot of infrastructure on it.