Dual SIM supported by most except Xfinity

While eSIM technology has been around since 2016-2017 and dual SIMs have existed even longer in mobile phones, why is it that Xfinity is one of the only carriers that does not allow 2 lines on 1 phone?

It's easy to say, "dual SIMs are not supported", but they actually are.  Why won't Xfinity allow something so useful?  Why are many other carriers supporting this but not Xfinity?

Xfinity, please fix this because it's not an issue and it just makes you look archaic.