You would think the Democrats know better, but they clearly don't since they have been giving Republicans more than they wanted for decades now--even when they had substantial congressional majorities. McConnell's plan is essentially do only what he wants, as apparent by the fact that he wants use to wait 9-11 months to fill a currently vacant SCOTUS seat in hopes his party wins the Presidency.
They proposed what they thought would pass, and at its core the ACA is still based heavily on the Heritage Foundations HC Reform from the 80's/90's. It was the Conservative solution to Healthcare Reform for 20 years before Obama got it implemented, and now they hate it because a Democrat actually passed it.