All B/R update speculation.

[Gunseng]

They've printed a lot of ways to hate on fetches, they're just not as astrong as just playing the fetches anyways.

A Wasteland with "split second" would probably do the trick . As a more serious suggestion, I'd love a Suppression Field on a 2/2 blue Merfolk body for .

[FourDogsinaHorseSuit]

A Wasteland with "split second" would probably do the trick . As a more serious suggestion, I'd love a Suppression Field on a 2/2 blue Merfolk body for .

It would need to be like a stifle that draws a card and has to be either free or 1cmc

[FourDogsinaHorseSuit]

A stifle land would maybe do it. But parity isn't punishing imo.
Like fatal push doesn't punish you playing creatures, or force of will for playing spells. Daze gets away with it because you can return a tapped land. Daze would be unplayable if you couldn't go T1:Island->spell->hold up daze.
You need to lose the fetch and I need to gain something. With stifle it's tempo.

[rufus]

Lands are an easy and well-known way to make chase cards. There are also legitimate 'quality of game play' reasons to limit how easily people can mess with lands. I don't think that WotC has any real incentives to print effective fetch hate, but has strong incentives not to.

[dte]

It would need to be like a stifle that draws a card and has to be either free or 1cmc

Just a Stifle that costs a phyrexian blue instead of just blue. That works OTD and should be good enough to see play enough to really push the fetches out.

[FourDogsinaHorseSuit]

Just a Stifle that costs a phyrexian blue instead of just blue. That works OTD and should be good enough to see play enough to really push the fetches out.

Turn one dreadnought?
Go ahead and fetch. I don't care anymore.

[PirateKing]

They moved away from lands that don't tap for mana which does eliminate design space for the enchantment effects like Tabernacle or Glacial Chasm.
Just a Land that said "Whenever a nonbasic Land enters the battlefield, it's controller may pay 2 life. If they don't, it enters the battlefield tapped."
Give it Protection from Lands as well, because that's weird and why not.

You'd need continuous effects, 1 for 1 like Stifle isn't good enough anymore. Hence the Grafdigger's Cage example. Effective turn 1 on the play that proactively punishes the strategy, is symmetrical so you can't just also jam the same strategy.

So something that is a land or you can play off a basic land to make your basic only mana base on par with the 4 color greed piles.
Seriously just Cage for lands, "Land cards in graveyards and libraries can't enter the battlefield." would be huge as a 1 drop.

[dte]

Turn one dreadnought?
Go ahead and fetch. I don't care anymore.

Maybe adding "you don't control" would be a good idea :)

[FourDogsinaHorseSuit]

Maybe adding "you don't control" would be a good idea :)

NO!

[Zoid]

Whenever an opponent would shuffle, they instead put a card from their hand into their library and then shuffle.

This would be a nice effect to also punish other tutors just like Leonin Arbiter does.

They won't let cards attack the land base anymore before T3-4 or with replacement effects.
Given that they have ramped up the frequency in which they print dual lands from 5+ per cycle/year to 5+ per set that makes sense because even Standard decks can now work without basics almost unpunished.
I 'member when 5C control in Standard playing [card]Cruel Ultimatum[/card] and [card]Cloudthresher[/card] was considered an abomination.
As most new chase cards are so undercosted/give so much instant advantage color is basically no resource anymore.
In Legacy with actual hate and requirements for pitches basics and splashes are more restrictive even with access to duals and fetches although still very easy.
Considering how much they refer to the color pie I'd like to see playing more colors an opportunity cost again.