Without Yawgmoth, Thran Physician, Golgari Yawgmoth would not exist
However, most larger formats have a multitude of cost-reduced spells, such as the engine offsetting the cost of Pitch spells, letting a Beanstalk player accelerate through their deck without losing on the tempo axis
Mindstone can be that step and then it is pretty irrelevant, if you can make 9 or 10 mana mos of the time won't make much difference while an extra card really can
Vraska the Unseen is really pretty bad compared to the good planeswalkers but being a planeswalker she is still unreasonably playable
They are better in modern which has many decks capping out at three mana but they are still great in cube
But if there isnt a 2 or 1 power creature on the board, Garruk is going to be stuck on his weaker side