You can't take an AWS VM and fire it up on DigitalOcean without trial by fire. VM's should be portable but they're not because cloud providers don't want them to be.

For a while everyone was locked into AWS but now that there's other options some companies want to hedge their bets, or even run parts of their workload locally.

Since the VM space is all proprietary now people are moving one level up and building a consistent environment above it. I fully expect docker to become proprietary in a couple years and the cycle will begin again.