I'm sorry but this is just sad.
How often are both adc and support in lane at the same time long enough to actually quest?
What are they trying to do? take a class that often is 3-4k Gold behind anyone else and make them 6-7k behind?
This isn't just a nerf. This is a 25--30% of the game utter destruction of gold income.
Furthermore, post lane phase, supports will more or less have NO INCOME because they can't reliably CS, and teammates are always on the move, where there's not always an opportunity to follow them.
Just ...... Wow.
For the record: No CS top lane had legitimate drawbacks: If you were ganked, or if the opposing laner got aggressive, it almost always sabotaged the attempt to 0 CS and gave free lane control to the other laner.