Madam Mim Elephant is a 3|7 Character that can move 2 damage counters from her to chosen opposing Characters, potentially banishing low-health characters or dropping them low enough for your attackers to banish them
If Mufasa survives, you can use all of your ink, quest for 4 Lore, and then use all of that ink again
Outside of Sapphires tendency to ramp ink or mana quickly, or the ability to filter through a deck, there are a handful of similar bonuses from just having Detective cards in your deck
According to EDHREC, we see Ranger-Captain of Eos in 123,367 lists, which equates to around 4.5% of all decks playing white
At the same time, you need lore to advance towards victory, so questing with a powerful card is often worth it for the points gain even if it opens it up to attack
When Rise of the Floodborn first came out, it seemed Sisu might be the most valuable card in the set