Its because the Dems and Repubs all thought Hillary was going to win, banking on it. They never had any intention of having to replace Obamacare. They were caught completely off guard with no plan in place.

Now they've all bought into this deep state cabal Russia narrative, "we're gonna impeach Trump...just as soon as we find the smoking gun!" So the Dems and Repubs keep kicking the can down the road, no clue how to replace Obamacare and no desire to.