When it comes to a Get, you don’t want to write a Get that only some poskim hold is kosher. Because if such a Get is utilized while other poskim hold it isn’t a kosher Get, then she potentially remains an eishes ish and future children with a future husband will be mamzeirim according to the poskim who held the Get wasn’t kosher.
Of course in the Gemora when there was a machlokes where Beis Shammai held a person was a mamzer but Beis Hillel held the person wasn’t a mamzer, Beis Hillel would identify those people to Beis Shammai so that they shouldn’t marry someone they held was a mamzer, even though Beis Hillel didn’t hold so.