I suspect you're taking a much more cynical view of a strictly business policy. MSN serves far fewer people than other Microsoft products and their numbers have decreased over time. When Windows 10 was introduced, and even before, Microsoft WAS terribly slow in migrating the 32-bit MSN to a 64-bit product. That caused big problems with people with newer computers. Currently, part of the installation of MSN to your computer includes the older Internet Explorer, which one needs to operate MSN. Edge has replaced all other aspects of Internet Explorer. Once Microsoft gets around to introducing a new MSN that's 100% compatible with Edge, your computer's Internet Explorer should not be needed.
I suspect it's a big task, but my quibble is that we're paying a full price for a yearly subscription and we're getting no rebate for this semi-useful outdated MSN and they're dragging their feet to fix the damn thing.