Aside from categories like instant, creature, and planeswalker, cards in Magic: The Gathering can fulfill specific roles like spot removal, utility lands, and certainly board wipes
Their Future Sight-like ability can spew a stream of cheap threats from the top of your library with ease, effectively drawing you several cards per turn
This is certainly less powerful than Second Sunrise, a card that singlehandedly fueled a degenerate combo deck (and that has a similar effect to a six-mana card), but that doesnt mean it isnt also broken
That latter one is nasty to make mana from a mana rock like Gilded Lotus or Thran Dynamo
Interaction You cant play cEDH without it, and you also cant really do a commander-centered combo deck without it, especially so