Does MagSafe enable the use of existing tripods?

Are the MagSafe magnets in the iPhone 12 series strong enough to reliably hold the phone, only through magnets, to a tripod?

Magsafe is for charging not mounting; it helps align the charger. Even if they are strong enough to hold the phone, are you willing to put a $700USD (or more) device hanging by just a magnet? You use the 1/4" or 3/8" screw posts to securely hold camera gear with proper mounts (hot/cold shoe), why would you risk your phone this way?

Otherwise it seems like an obvious contraption, one that enables users to use one of their existing tripods rather than acquire a tripod specifically for just this edition of this phone.

I don't see what MagSafe has to do with a tripod in any way. You didn't need MagSafe to use your phone with a tripod before MagSafe. I literally just purchased this Manfrotto Mount (see below) to hold my iPhone on a tripod and additional 1/4" posts to attach LED panels.