Co-operation is good, a CoOp is always good!
Ideally somehow the advertising part of it could get consolidated -- so we don't have to join 42 cat groups in order to spam 'em all ... and we don't have to read the spam from 42 cat groups to find the kitten we want to buy
In favor of ...
Anything that makes it easier for the buyer to find the seller, and vice-versa, so that shopping for the desired cat is less difficult, and selling the desired cat is possible because the person who wants it can find it!
I hope the Co-Op will help smooth over some of the silly quarrels of yesteryear