Restricting workshops could, for instance, make colorless eldrazi a much more attractive option in the format, since right now it does not see play since it is considered a mostly inferior version of what shops was doing. Colorless eldrazi just so happened to be a pretty decent check to decks that run Misstep, since most lists runs no 1 drops, and run Cavern of souls to make FOW much less powerful, and therefore also devaluing MM even further since you cant use it as convenient pitch fodder. So maybe restricting shops has a cascading effect that adjusts the meta so MM is not such a powerhouse.
Let me break it down into
- restricting Workshop making Eldrazi more playable
- more playable Eldrazi rendering MM restriction unnecessary.
Regarding 1, restriction of Workshop will not make Eldrazi more (or less) playable, at least I cannot see it how. If I have to make a stretch, it just suggests that the vacant where the Shop decks left will be occupied by inferior choices, be it 'Colorless Eldrazi' or any other decks, but not necessarily make any other deck more competitive or better position. In contrast, storm deck is better positioned if Shop decks are gone.
For point 2, if Shop occupied more 50% of the meta, MM will be irrelevant more often than not as well.