I have stated this in other similar threads but will reiterate my feelings here....In other formats (standard and modern primarily) when the DCI bans cards, there is always a segment of the player community who's pet deck gets nerfed, and they throw their hands up, put their cards in the closet and say "I quit!". Maybe this hits some local scenes harder than others, but when it comes to larger events, the impact of these folks no longer wanting to play is almost meaningless, there will "always" be more players who want to play these formats (especially standard).
This is very different from Vintage, where the player base is significantly smaller and not growing at any recognizable pace. Restricting something like Workshop, whether validly based on data and statistics or not WILL cause people to quit the format, plain and simple. If your response to that is good riddance and grow up, fine; I personally do not see how a format that struggles to meet attendance floors for its most prestigious events can possibly withstand a restriction that would alienate a whole segment of players.
Maybe the critical mass of artifacts that suck in every other format but are mega playable with a 4-of-artifact-only black lotus that never goes away is real, but I do not think the impact of players that will literally stop playing vintage can be ignored. Is it fair for these folks to hold the format hostage...no of course not, but I do not think that a Shops restriction is the way to go right now. I would rather see sweeping restrictions of Sphere, Ravager, and Revoker, In addition to Mentor, Preordain, and Mental Misstep.