You need to look at it a bit differently: it’s not that 38 states are needed to approve amendments, but rather that only 13 states are needed to block them. And Republicans have been very effective at electing politicians at the state level. Republicans have total control of 28 State Legislatures, and also hold the Governor’s seat in 23 of them.

So, any amendment that manages to get through Congress (and the filibuster) will have to be approved by a bunch of these State Republicans. So pretty much any policy that that can be considered liberal will be DOA.

In fact, Democrats have more to worry about in the other direction. They only hold 18 State Legislatures, holding the Governor’s seat in 16 of them. That is perilously close to the threshold of not being able to block amendments. If Democrats lose just a few more of those sale states, the the next time Republicans hold majorities in the House and Senate, they may be able to force amendments through that the blue states don’t like.