I initially figured they were implementing SMS authentication specifically to stop dummies from making 100 accounts. This reason seems to come from a place that assumes you need to protect user info.
I doubt xenforo knows what Sherdog is. They probably just recommend it to every customer because they assume everyone wants added security.
You guys got me using whatsapp now so I can stay in touch with legends like
@StonedLemur
2FA should be optional for the user unless there is some other reason not being said for this implementation