“Microsoft 365 Enterprise IT admins will be able to alter the policy, but those on Microsoft 365 for business will have to manage this change on individual machines.”
Weeks ago Microsoft said it had a responsibility to respect user choices and would lead by example with its own products. Now Outlook links open in Edge no matter what default you set, and Teams is next. Big enterprises get a policy switch. Small businesses get to fix it one PC at a time. Microsoft calls it reducing task switching, and it means switching you to Edge.