See Orion’s comment above about spatial locality. MGRS does have some locality but takes practice to understand, because it interleaves latitude and longitude so you have to do some mental acrobatics to figure out if two points are near one another, outside of the first 3 characters (top level grid).
I notice that use cases don’t come up often in this discussion. What are we doing with this point reference? Reading three (2-3 syllable?) words to somebody over a spotty phone connection actually sounds pretty good, and certainly better than reading 11 character names (especially if one or both parties don’t know a common phonetic alphabet), or let’s say 12-20 digits of a decimal lat/lon. Plus Codes could arguably be better (though I think it can have the same phonetic-alphabet problems) with a useful location in about 7 characters, assuming both parties know the general area being referenced. And of course, that’s one pretty specific use case and there would be others where different systems make sense. Do I actually want the easiest system for remembering an address? Could be completely different.