It is the fact newer scamcoins ruined prices and trade volumes for previously added altcoins. I think exchange owners will rethink adding any more pointless altcoins which is
what gives a chance to YAC. It is different. YAC launch was not good, many got too much YAC in short period of time due to low starting difficulty but things are going better.
Once "weak hands" dump their YAC and move to other altcoins, YAC will stay and grow stronger and that is what other exchange owners might recognize as positive signal.

As for the FTC, CNC and other crapcoins, the only thing I see happening with them is removal from exchanges. There is really no need for any of those altcoins since they add
not much to cryptocoin scene.