H1B's take back what they learn, Microsoft. Their governments take back an indoctrinated acolyte.
I can understand mastery of a toolset.
Person A comes to work skilled and certified in Visual Studio, C#, and SQL Server.
Person B comes to work familiar with the aforementioned products but as well is familiar with Oracle, Ubuntu, and Java's suite of tools.
Person C comes to work familiar with SQL Server but generally only has an administrative background.
So management has these three people to work as a team to derive a product within three months.
You can only imagine the difficulties that transpire as a result of conflicting personal views.
So from a management world view:
You won't an employee that will take the resources you have and provide a product in a short time with the least difficulties.
H1B's are the Person A's.
Skilled U.S. workers are the Person B's.
Corporate executives are the Person C's.
This is changing as more U.S. workers are attempting to get certifications.