Cartridge output question.

An electrical engineer of the old school with many years experience tells me that cartridges should have an output of close to 5 millivolt, that that is the way to setup a vinyl system where a phono stage sees a greater output than today's cartridges.
What are the advantages of low output moving coil.
As for me I prefer the lomc, should I consider the high outputs.
He has a phono stage that works great with the high output cartridges, what modern high output cartridge should be considered so I could give his phono a try.