Slavery is a great example...it was around for 250 years before it was repealed (if that's the right term...). ACA has mostly not even gone into effect.
My issue is with the process, the holding hostage of the country's well being to try to accomplish a goal, and then saying the other side is responsible for "not negotiating." Using a threat that will affect millions of Americans to accomplish a legislative goal...it's not appropriate. Why should Democrats negotiate under this type of threat? Congress has every right to repeal laws, but we don't know yet how this law even affects people. As far as I know, the vast majority of people will not be affected at all...if you have health insurance through your employer, for instance.
But again, point taken about repealing laws, of course it has to happen sometimes. If this law is as disastrous as some seem to think, I will help repeal it! But easy on the shutdowns!