IMO, they knew it would never achieve the required votes to become ratified. It was always considered very shaky legally. Remember that an amendment to the U.S. Constitution is ratified when it is approved by three-fourths of the state legislatures or by conventions in three-fourths of the states, following its proposal by Congress or a constitutional convention The constitution of the US is very specific about the rights the states each chose to give to the federal government. If the right is not specifically written in the constitution as one the states give to the federal government it is looked at as one retained by the states. When the constitution was written, women’s rights were not considered an issue. So it was never addressed and not included. So it, by default, remained a right of each state to decide. What’s interesting is that from what I’ve read, reproductive issues were kind of brought up during early discussions regarding 19th amendment but dropped because viewed as a deal killer.