Yes my statement was probably a bit too broad. I meant any pasta with a sauce you generally don't want butter (or oil) on, as it causes the sauce to stick less to the pasta. Which is the whole point of having the sauce in the first place.

I actually have. A can of tomatoes is (or at least was back then) cheaper than a pack of pasta, and can also last for more than 1 or even 2 servings. If I add (just) butter to the pasta, I'm making it worse because I'm one of the seemingly 5 people on earth who don't like butter.

But my comment was meant for pasta with (any) sauce, see my other reply.