It seems the whole idea of WRC2 Pro turns into hidden pay driving. Not only M-Sport, look at Citroen now:
Citroen Racing
''Proud to support our Citroën
customers: Mads Østberg & Co-driver Torstein Eriksen will race in WRC2 Pro & behind the wheel of the #C3R5 - from Rally Sweden.''
source:
https://www.facebook.com/citroenracing/