For example, if a spell requires that you exile cards from your graveyard, you can exile cards from any graveyard
It's one of the most popular Dimir commanders in terms of play rate, though one of the least popular in terms of how much you want to see an opponent playing it
On its own, it's gorgeous, but with the rest of Destined Rivals, it truly stands out as a brilliant chase, one that deserves to be above the rest, even that SIR that's too expensive right now
Fairy Zones Weakness manipulation can completely warp matchups, while Full Moon Rondo scales effectively in Bench-heavy formats
You need to get more from your cards, and your creatures in particular, than you can get if you have no way to interact with your graveyard
Gitaxian Raptor If proliferate decks become good enough they can churn out several counter bumps a turn, then this can potentially get in for a solid 3-4 damage a turn