Grasp of Fate, Oblivion Ring, and Banishing Light all allow for really flexible removal
But creating a Blood token does not count as investigating, and more importantly, sacrificing Blood requires you to also discard a card before you draw
Hitting creature-lands doesnt matter that much, and using the awaken mode of Planar Outburst was useful sometimes, but gaining a few extra points of life from Fumigate is a really big deal
Blue offers to bring a lot more to the archetype with loads of self mill and recursion effects but doing so is a much bigger commitment
Instead, Maralen allows each player to spend their draw step tutoring for any card they want at the expense of 3 life, and that can lead to some interesting twists in gameplay with everyone getting their favorite cards on demand
You can still play lands only during your main phase when you have priority and the stack is empty