In addition, all MM cartridges are designed for a phono input impedance of 47K ohms, which is what virtually all MM phono inputs have. OTOH, the optimal input impedance for MC cartridges varies widely.
High output MC's of the type mentioned by Hagtech are designed to work with the limited gain of a MM phono stage, so they're designed to work well into 47K too.
Medium and (especially) low output MC's that need more gain almost always need a lower impedance too. A few really low output MC's (.1mv or so) need an input impedance of just 2-3 ohms and a ton of gain too - at least 70db.
Since the gain and input impedance requirements of MC cartridges varies widely, careful matching between MC cartridge and phono stage becomes vital. Few dealers have the knowledge to do this properly any more. More than a few phono stage manufacturers don't understand it any better. This can come as quite a shock when you buy an umpti-thousand dollar phono stage, an umpti-thousand dollar cartridge and discover they don't mate well.
Hagtech knows all this, better than me, and his phono stage matching advice is always sound. I suspect he didn't want to scare you with too much, too soon. I'm not so nice! ;-)
Doug