As for Graverobber: 1: It's a trap so it's too slow 2: it only targets spells 3: Because of how many restrictions are put on spell cards these days finding a useful target for Grave Robber's effects is nigh impossible 4: There is a crazy LP cost
1 Secret Rare (a second copy of 1 of 6 of the Ultra Rare cards), with a small chance of being Starlight Rare instead of Secret Rare
But, as pointed out in the comments, the rules here are out of date
After all, it might be embarrassing to have a chic Yu-Gi-Oh
While that aspect in and of itself isnt necessarily the reason for its banning, it certainly contributes to the negative experience the card creates
If the opponent's card in the same column as yourself leaves the field, you can fulfill some opponent-dependent conditions, and the effect of making his Mekk-Knight his Special Summon from your hand