I get that when given the option, many people will just grab the best in slot card - its one less card you have to worry about, and it saves you having to spend time brewing your deck, right
Mishra's Bauble, one of the best eggs in Magic, isnt as broken, but being a 0-mana cantrip (even if the card draw is delayed) makes it a mainstay in Vintage and Modern
Well also only be looking at the main set, set code SPM, and not SPE or the MAR bonus sheet
Riverchurn Monument is the kind of mill card that scares me, because it tends to combo with a bunch of mill favorites like Bruvac, Phenax, God of Deception, and ways to make players mill a lot of cards (Maddening Cacophony, anyone?)
Since they can always bounce themselves, they give you a starting place for repeated (1) ETBs, and (2) creature casts