Post-sideboarding there's a bunch of specialist hate that can come in. Mainboard there's a single copy of
Bojuka Bog, which is there just in case, and then there's a couple of
Relic of Progenitus. There's so many archetypes that are graveyard-centric, even delver decks make good use of the graveyard sometimes.
Exhume decks, tormented existence decks, even most control decks use the graveyard with things like
Gurmag Angler,
Chainer's Edict,
Forbidden Alchemy,
Deep Analysis, etc.
Pharika's Libation / Feed the Swarm give the deck an out to anything from enchantment control decks to Pestilence and Oubliette from mirror matches, or can always double as an emergency removal spell if need be. It's always been green and white having the ability to destroy enchantments and never anything else, and it's a nice change to the colour pie.
One of the hardest decks - once online - to deal with is tron. Choking Sands helps slow it down, or even turn it back offline for a short while. Enough time to stabilise hopefully. Not getting blown out by a massive Rolling Thunder, or maybe a Fangren Marauder would be nice. I suppose even against some other things, like some sort of zoo landfall deck with a heap of bounce lands and dual lands would be okay, but the point of the land destruction is to destabilise mana bases, not just to slow down or annoy the opponent.
Duress is just genuinely a good card to have. There's so many aggro / creature-based decks that it's not very good mainboard, but against other control decks, combo decks (which are generally in a control shell), or any sort of blue deck generally it's basically a Thoughtseize. The ability to take a noncreature card, which could be anything from a Pestilence to a countersepll, a random draw spell to a combo piece. There are just so many good targets in so many matchups, but also so many bad matchups for it too. Sure, elves often runs Spidersilk Armor, even if just in the sideboard, it's an okay target but it really doesn't achieve that much, considering you can run an evindar's justice, for example, instead and catch out 3-4 creatures rather than just a single one that doesn't even do that much.