Is putting ketchup on mac and cheese wrong?

Yes, it's like poison.

Yes. At least I think so. It's got its own sauce there. Don't see the need for an addition.

As long as you don't eat it, no.

Yes

I dip my steak in ketchup, so I'm not going to judge.

Very wrong, dude.

Fie! Fie!

So, so wrong. 

Even Satan would be offended at the behavior of somebody who puts Ketchup on the wholesome macaroni and cheese.

ketchup is the greatest condiment known to man,
 
it hits all taste buds in a gentle sweep.
 
i hate mac n cheese though

that's fucking nasty brah

I don't like anything with ketchup on it, with the rare exception of meatloaf (the food not the singer). 
 
So no. If you're doing that, add some ground beef and substitute tomato sauce instead. You kooky guy.

"I dip my steak in ketchup, so I'm not going to judge. "

That isn't even close to as wrong as this. 

Which brings me to my next point, yes, this is horribly fucking wrong.  You have made an abomination of the culinary arts and should be punished in the most horrific and unimaginable way possible... like being forced to eat ketchup on mac and cheese.

Depends,
Home-Made mac & cheese, Yes that's blasphemy
 
But boxed shit like KRAFT DINNER 
It's pretty damn good, Though I prefer a small amount of BullsEyes BBQ sauce....
And bacon.

Ketchup doesn't belong anywhere except hot dogs. I've never eaten this mac and cheese thing you speak of, sounds like typical nasty american lazy food, but I presume cheese is involved, which instantly makes it unsuitable for ketchup. 

Ketchup can go on any meal you want. Adds flavor.

No, 'tis not wrong at all.

No, I do it all the time, ketchup is almost always great

Yes -_-

" Ketchup can go on any meal you want. Adds flavor. "

Macaroni and Cheese and probably one of the most over rated dishes humans have ever consumed. I'm not saying ketchup would save it, but it certainly couldn't do it any harm.

That is what Hitler used to do. 
 
You are like Hitler. 
 
Hitler failed. 
 
You fail.