Every now and again a three colour midrange deck using white would rise to the top of the pile and give you a whole 3rd way to pack white cards successfully in cube
Running Sram and Puresteel Paladin in your deck means you're not down a card when you play Equipment and you have more opportunities to draw creatures or synergy pieces for your Voltron game plan
Some cards care about mana abilities too, like Moonsilver Key, which can search for an artifact with a mana ability, or Battlemage's Bracers, which copies an ability unless it is a mana ability.
This article is the first in a series of content that I have been producing with the aim of conveying the result of everything I have absorbed about Commander along the way
Red, being one of the most starved colours for card quality, often sucks this up
They could have put those designations in again, but no, they made it easy on us for the Spider-Man sheet, designating all of the cards as mythic