I go to two different grocery stores to get different vegetables because they have varying quality. For example, if I want tomatoes I go to store 1 and for onions I go to store 2. For carrots I go to either because they are fine at both.
So if two instances have tomato, onion, and carrot magazines/communities with similar quality patterns I might want to sub tomatoes at one, onions at the other, and carrots at both.
I just want an easier way to find all of the instances that have onions so I know what I might be missing at the local farmer's market. Or find out that a new farmer's market opened up!