This is wrong on every level, you know what else shut off the combo, and was easily killed everytime it was played ? Thalia for 3 mana, and it also made their tap lands come into play tapped, and never once was Thalia a problem for Copycat decks.
The problem is you are combing a combo deck that wins on turn 4 with a control deck that doesn't have to do anything, and can sit there and draw cards if you do nothing. Though recently its turned more into a just a 4 color value fest.
Right now I did the math, and according to mtggoldfish Mardu Vehicles and Copy Cat decks are 75% of the metagame ..... almost 50% alone is copycat decks, and you think its still ok for that deck to exist ? We've seen 2 cards that deal with it from this new set, one is a 4 mana cycler that you have to go get a DESERT for, just to deal 1 damage, and the other is Mangle horn, a 3 mana 2/2;
Meanwhile here are the things that the copycat deck can now play, Essence Scatter, Pull from Tomorrow,Reduce// Rubble, Failure//Comply, Cast out, Censor, Dusk // Dawn
Theres literally no point in playing standard if some part of copycat doesn't get banned; because it will take over the meta in one form or another. Remember when you were all saying "oh man its not as bad as you think" and "their are answers to it"..... well yes there are answers to it, and they all exist in 1 deck, Mardu Vehicles.
Copy cat has pushed all of the fair decks out of the format. The numbers dont lie, the METAGAME is 75% between 2 decks, and 50% of them are copycat decks. They would need to print almost 2 - 3 answers per color to come even close to hating that deck out.