As long as Melira is on the field with Phyrexian Vatmother, you wont receive any poison counters on your upkeep if you need more time to draw into your win condition
It's important for mechanics in Limited to be able to function well when they are contested, meaning that you can't make your deck entirely out of one mechanic
Preston, the Vanisher Preston, the Vanisher has a very unique ability
The Rich Get Richer Amber Steel, Ruby Amethyst and Ruby Sapphire have been routinely amongst the best decks for the entire Into the Inklands format
The label applies only to Standard expansions.
It varies from group to group, of course, but often EDH is the format players turn to for wacky games with weird cards, so hyper-efficient insta-win combos can sometimes feel incongruous with that zany aesthetic