EA policing steam IDs

Why is EA using Steam IDs in game rather than EA IDs?

Friend just got a 3 day ban for his Steam ID which is ridiculous. His EA ID is well within the TOS for EA but the game shows Steam ID rather than EA ID with no option to choose. How do you have the right to police someone's name from a different platform when it would be so easy for you to just make the EA ID display instead? Why even require us to connect our accounts to EA?