The parties weren't yet ideologically sorted. The Democratic majority included dozens of members of the Blue Dog coalition, a conservative group who (among other things) didn't support healthcare reform.
Also the us Congress is blocked by the senate needing 60 votes/supporters to reach cloture on every single bill, except the once per year thing that got the bbb passed. So it's very easy to block the other side. https://en.wikipedia.org/wiki/Reconciliation_(United_States_...
