Your point is well taken, but I would assert that the early activities of the Progressives were the first steps of the fascist movement... brought to its logical conclusion by Mussolini.
This is the crux of the issue here... I will concede that the progressives did start the ball rolling, but TR and company as stated before did not have absolute control over the populous nor did they instill the draconian laws that the Fascist of Europe did...
Was TR what we would consider a model conservative today... By no means.... but his actions and they way he ruled did not rise to the level of fascism...
I think the other point that needs to be mention here too..
is really around and after WW2 the political parties both Repub and democrat did it flip-flop in their policies and plat forms... so our political parties of today... hold only a minimal amount of similarity to those of the past....