They can respond to this by tapping all of their lands, but it means that they only get one phase to cast things in
For Standard, they just printed this combo kill Sanguine Bond as Enduring Tenacity
7 Pair O' Dice Lost Can Return An Entire Graveyard To The Hand Spells that return cards to the hand are often a mixed bag, either returning only one at a time, very specific types, or having other restrictions
Best White Token Commanders (God-Eternal Oketra, Prava of the Steel Legion, and Darien, King of Kjeldor) Mono-white token decks can be built a lot of different ways, as represented by the wide array of effects of these legendary creatures
Brainstorm also supports top of library synergies and protects against hand disruption to a point so even if you are light on shuffles and self mill effects there is good reason to run it
Third, it oozes black