Respect to you for not losing fish to ick.
Most of my fish was purchased through live aquaria back in a day, with free shipping and 14 day garante, so not really taking risk on quarantine a fish.
...But tell me honestly, would you go and tell a new tank owner to go ahead and drop a fish strait from a store into display tank? I mean ick yeah, good chance of fighting off naturally IN Healthy/Mature tank. Which most new tanks are no where near that, 7 out of 10 new tank owners will have a fish in tank before a tank is even fully cycled.
...But what about velvet, brook, uroema, things that going to wipe tank down in days. You think a new reefer is knowledgeable enough to spot a sick fish in a store?
I know It wasn't the case for me when I started, for me it was a combination of tank not mature plus ick and velvet problems that I would say in first 12 month I lost about 10-15 fish in my fist year. So yeah, I would definitely still quarantine new fish, and I would suggest to any one to quarantine new fish. Its simple ignorance and gamble not to.