We took one more step recently as we prepare to turn off the HOSTED XAML agent* in VSTS: any VSTS account created after mid-May 2016 won’t have a HOSTED XAML agent provisioned at all. A side effect of this occurs when you try to hook Azure Web Apps or Cloud Services to VSTS for source control \ continuous deployment in the old Azure Portal, which only creates XAML build definitions.
Customers will see the message below.
The workaround is to use the new Build and Deployment Services in VSTS with Azure Endpoints instead. Here're some helpful links. These are written from the perspective of Release Management so you will need to filter it a bit to pick out just the BUILD parts, but they provide a good overview of the process.
*We're disabling the hosted XAML agent. We will still support XAML... for a while at least... in VSTS, but customers will need to set up and maintain their own private controller and agents to do it.