I did something distantly related with a card that put itself on your Tavern Mat and counted copies there. Not sure whether using a common pool like the trash doesn't create a prisoner's dilemma. Maybe if it's a great tfb target, but on most boards spending buys and time to build something your opponents can get just as easily is a waste. Forager you can simply just use to clear out junk, so the problem is not inherent in the card itself but in how you use it. Well, i guess you can also gain the majority of these, but it still seems more problematic than Forager if it offers nothing else.