It's probably a blanket requirement by the MSFT legal team so they can just release everything as "(c) Microsoft" instead of "(c) Microsoft and 999 more contrib

It's probably a blanket requirement by the MSFT legal team so they can just release everything as "(c) Microsoft" instead of "(c) Microsoft and 999 more contributors, one of which has actually forgot to put their name in the AUTHORS.txt and thus we're technically violating the terms of the license"