In the CLA it says:
conveys certain license rights to Microsoft Corporation
(and has a whole copyright grant paragraph)
But the README only says:
declaring that you have the right to, and actually do, grant us the rights to use your contribution
This is completely misleading, and in my opinion dishonest. A submission of code under MIT or GPL license without a CLA would grant you the rights to use the contribution. The CLA grants essentially all rights for Microsoft to do whatever they want.
Anytime you have a CLA you can guarantee the project has their own interests first. Let's just hope those interests are benevolent :/