I think Azure is so relatively popular because Microsoft is the only consultant company who owns a cloud.
Generally speaking, for any piece of software -- cloud infrastructure, (managed) database, CRM system, operating system, office suite -- Microsoft has it and has consultants you can hire to help implement it in your company.
That's why Microsoft is doing well, as car as I can tell.
Two other reasons:
1) They have the consultants and more than likely an existing business relationship for Windows, Exchange, etc.
2) They are not likely to compete with you - Amazon is trying to compete with everyone and nobody wants to fund their own demise.
Generally speaking, for any piece of software -- cloud infrastructure, (managed) database, CRM system, operating system, office suite -- Microsoft has it and has consultants you can hire to help implement it in your company.
That's why Microsoft is doing well, as car as I can tell.