Sure, but in practice if you have any complexity in your stack then it's going to be a PITA to from Azure to AWS (or vice-versa).
If you're just running instances then maybe it's not too much work - though you're still going to have to think about backup / restore, access control, autoscaling (maybe), cost tracking / allocation, etc...
I'm sure Microsoft are banking on a profitable percentage of YC companies becoming so wedded to that Azure systems that the opportunity cost of switching to AWS is too high.
If you're just running instances then maybe it's not too much work - though you're still going to have to think about backup / restore, access control, autoscaling (maybe), cost tracking / allocation, etc...
I'm sure Microsoft are banking on a profitable percentage of YC companies becoming so wedded to that Azure systems that the opportunity cost of switching to AWS is too high.
Edit: Typo