Why were liberal or progressive politics so weak in the 1920s?

In one sense, the "Roaring '20s" were a liberal time.  People were enjoying life in a way that expressed all sorts of freedoms.  There were forms of music and dancing and partying that defied traditional moral norms.

But beneath all that, the decade of the 1920s was "actually a time of reactionism, conservatism, and division," according to "History is Now" magazine.  Prohibition was in place, making alcohol sales and consumption illegal.  Radical political groups were targeted for suppression by the government.  Women had been given the right to vote (in 1920), but that didn't mean that the majority of the country was eager for women to take an equal place next to men in society.  Ultimately there was more of a conservative mood in the country (wanting things to stay the same) than there was any big push toward liberal or progressive change.  That was evidenced by the fact that in the presidential race of 1920, Republican Warren Harding got 60% of the vote compared to 34% for the Democrats' candidate, and in 1924 Republican Calvin Coolidge got 54% of the vote compared to 30% for the Democrats' candidate.  Even adding the 3rd party Progressive candidate's votes, the Republican (conservative) side still had the strong upper hand.

Because he proposed that all the treaties should be made through the league of nations.