Except that was not the assumption prominent Democrats made with each loss after 1972. McGovern, Carter, Mondale, and Dukakis were all said to have lost-or lost so convincingly-because they were too liberal. For that reason most of the serious candidates for the 1992 nomination ran as relatively conservative candidates. Tsongas was more conservative than Clinton was on fiscal issues.
You can say that categorization is unfair-and to a point I'd agree. Carter contrary to his image was not that liberal in the political context of the 1970's. Dukakis ran as a post-partisan technocrat rather than a true liberal in the Kennedy 1980 vein.
But given how the party reacted in 1992 the conclusion that the party was too liberal must have stuck. Otherwise candidates like Clinton and Tsongas would not have been as successful as they were.
Throughout this period the Democratic Party had the opposite reaction to loss as the Republicans. I'm not sure defeating Clinton would stop the ascendency of that viewpoint in the party.