Yes, this brings back memories of all the reading of mono, mono carts, mono switches et. al. before I made the leap.
Many camps with various beliefs. One thing to keep in mind, there is no vertical information in a mono groove, only horizontal (sides). Unlike a stereo groove where there is info both horizontal and vertical within the groove. Thus, theoretically, if you have a very clean nice period mono LP, all the info is there no matter how high or deep the stylus goes.
But yes, if you have an abused mono LP that was played many many times with a worn out conical stylus, a new fine line stylus would in theory go deeper into (below) the ‘damaged’ grooves, and sound better.
No doubt though, I would say today, most all the carts, even the Ortofon 2M Mono (with a spherical stylus) would have been better than most all carts available when these old albums were released. But I’m sure some would disagree with that too 😁