Let me guess..
Their toolset only assists migration *to* their network, not away from it..
Welcome to Hotel Azure. You can check out but your data never, ever leaves.
Microsoft has revealed the Azure Migrate tool it announced as supporting lift and shift from on-prem vSphere to Azure will also become capable of doing the same for on-premises Hyper-V applications and applications in rival clouds. But the company’s stayed schtum about the identity of the mystery VMware partner that has helped …
"Their toolset only assists migration *to* their network, not away from it.."
No, 'their toolset' also includes options like Azure DR and StorSimple which replicate to / from on premises.
One of the major advantages of Azure is that you always have an on premises option - both in Azure Stack - and in running your own Microsoft Servers. Unlike say AWS where if you write for say Dynamo DB you are screwed if you ever want to move !