Yeah, Azure is huge. There are a lot of companies that see themselves as direct competitors to Amazon and refuse to allow any of their applications to use AWS. Walmart is a huge one with this -- if you want to sell IT services to Walmart, your product cannot run on AWS. They're not the only one either.

Azure also kind of just plays better with the whole Active Directory / Office 365 / Sharepoint ecosystem and many Azure products are substantially cheaper than AWS.