Balanced input mm phono preamp

Not sure I quite understand “why no point”. Unless one side of the coil is grounded (which is done by “some” MM manufacturers) one still has a notional a “balanced”, possibly more correctly “differential”, signal.

Sound Practices had a interesting Differential Input, split RIAA MM stage article and circuit penned by jc morrison, Siren Song. I don’t have the specific issue details with me, sorry. Your search engine of preference should find it.