Unlike Oscars and Midas that have been in the hobby for almost a century, and sort of become as domesticated as a fish can be.
M. argentea only showed up in the hobby in the late 80s, and early 90s, and even then...due to their wild, lonerish and untrusting disposition, have not developed into the anthopamorhic familiarity, and doglike tameness that oscars, midas and some other more common cichlids have.
Perhaps they are too innately intelligent to trust humans, too rebellious to develop "Stockholm Syndrome.
It was first only scientifically described in 1991
Not saying they couldn't, if raised in a one person in a no other fish environment, but it may be highly unlikely.
So I believe what RD says is right on the money.
Of the dozen or so I have kept over a couple decades, none have come close to a golden retriever attitude.
I do find them to be one of the most beautiful and my favorite species to keep (albeit as a single species to a tank).
But my expectations for them being a "pet" are quite low.