Traditional Format

Why are mythic rares banned?

WotC originally stated that mythic rares were to be assigned to cards that "felt mythic" and unlikely to become format staples, e.g., Godsire.^[1] Instead, their intentions strayed when WotC began printing staples at mythic rare even if they didn't feel epic or deserving of mythic rare in order to push packs, driving up the costs of many decks. Examples of mythic rare cards that were obviously printed as such in order to sell packs include: Lotus Cobra; Warren Instigator for Goblin decks; and Scapeshift, which was upgraded from rare by WotC.

Furthermore, Richard Garfield feels that mythic rares were a mistake.^[2]

Why not (un)ban [card]?

While we are aware that some may want certain cards from Modern to be unbanned, it would make the format more complex than necessary and difficult to follow.
When making exceptions to cards, we run the risk of creating a kitchen table ban list and not clearly defining the Traditional format; e.g., One with Nothing is hardly powerful in Pauper, but since it was never a common, it cannot be played in Pauper due to its format's rules.

We are considering the possibility of running our own ban list after the format gains traction.

Starting with Ethiopian BIRRRR we've started experimenting with banlists and more deckbuilding rules, thanks to Eternal Witness.

Why the Planeswalker ban?

Planeswalkers are banned because they represent a design within the game that inherently generates too much immediate value, and are difficult to remove or interact with. Some Planeswalkers, like Teferi, Time Raveler and Nissa, Who Shakes the World, have effects that bounce creatures or create creatures, giving them a built-in way to protect themselves the moment they hit the battlefield, and nullifying creatures as a form of removal for them. Because they are played at sorcery speed, the player playing them will have priority after playing them, allowing them to get value out of them before the other player has a chance to respond, effectively nullifying certain forms of interaction that the other player may have for them, such as Fry and Lightning Bolt. The only efficient removal for them require black (e.g., Assassin's Trophy, The Elderspell, and Thoughtseize), meaning other colors are shafted in terms of having an effective way to deal with them. In addition, Richard Garfield himself dislikes Planeswalkers conceptually.^[3]