Galliardist
Major Contributor
The truth lies somewhere in between. You can demonstrate this by aligning the cartridge correctly for the innermost and outermost grooves, then measuring the distortion. I can't find the reference unfortunately, but I have read that this has been done and distortion was still higher when the cartridge was correctly aligned for the inner grooves.I disagree.
The linear speed is reduced, yes, but the real effect is ... more information per groove distance ... and that doesn't mean distortion.
Distortion happens when the cartridge / stylus / suspension cannot "track" correctly the information in the groove, and you have a more difficult groove to track, obviously ... but the IGD happens when the cartridge cannot read it rightly. With conical / eliptical styluses and MM cartridges not very good adjusted it can happen easily (MC cartridges have an improved internal motor, so even a conical works much better than MM)
Other source of IGD happens when a previously misaligned cartridge made physical damage in the groove ... that's irreversible obviously. Also dirt or static can create IGD.
(Of course this is hearsay without the actual numbers, but I can put it out there for someone to repeat the test)
Have you evidence that MC cartridges are inherently superior? Back when I was taking notice of such things, the better MM cartridges tracked better than the majority of MCs. I'm prepared to accept that this may have changed in the last couple of decades. That "not well aligned" line doesn't justify any claims, anything not set up properly won't work as well.