Many Commander decks are built around powerful equipment, with ways to change equipment between creatures for free, or effects like Sigarda's Aid to turn equipment into combat tricks
Sapphire was also notably missing another solid four-drop alternative to Belle, Strange But Special, and this fills the void nicely
For example, Sapphire is great at gaining ink but weak at drawing cards, so pairing it with Amethyst creates a much more balanced team
I might not be loading them into rocket ships, but I do want to be able to block flyers and get in free attacks on anyone with only a ground presence
A good early removal spell that doubles as a discard outlet is a pretty good rate, even at sorcery speed and with the restriction that you discard an instant or sorcery
It's strong everywhere, but it has enhanced value in archetypes that care about counters generally, +1/+1 counters specifically, proliferate tricks for multicolor brews looking to add loyalty counters for their planeswalkers, four and five-color decks, Commanders with evasion, Commanders with a power that, when increased by 1 get a faster kill, Equipment, Aura, and Voltron decks looking to get in kills with their Commander, and loads more
