In contrast the US and the UK, with their free speech absolutism (British hate speech laws weren't put into place until recently), were one of the few major democracies without fascist parties winning any major elections.
Those gatekeeping functions were lessened after the violent Democratic national convention of '68 (where there was a clash between pro-war and anti-war factions) and primaries became a thing that actually mattered (in 68 Humphrey was selected by backroom insiders who did not participate in a single primary in that cycle, leading to public outcry). However, the gatekeeping effects persisted because of the control the parties still had over advertising channels and the media; that control fell apart post-2000, which setup the conditions that enabled a populist like Donald Trump to actually be elected to the presidency.
So it's not free speech that kept fascists out of power in the U.S., it's institutional gatekeeping (in the 30's and 40's).
This point does not pass the smell test. Since 1968 the United States has become a vastly more tolerant, liberal, open and free society than prior to that point. You'd have to do a lot of mental gymnastics to say that the US is more prone to fascism than it was 50 years ago.
https://www.npr.org/sections/codeswitch/2019/02/20/695941323...
https://time.com/4516276/cable-street-battle-london-east-end...
(the giant murals of George Washington and the talk about "job-stealing refugees" is particularly apropos given the current atmosphere of the Trumpist faction)
It is obviously correct that once social norms have reached the breaking point that hate speech laws can become a cudgel used to further hate speech. The goal is to keep it from reaching that point.
It is in fact probably correct to say that in either approach once the social norms have reached the breaking point, that either positive or negative freedoms can be weaponized. Freedom of speech can be used to rally a lynch mob, and hate speech laws can be used to oppress a minority, once you have reached the point where a hateful party has widespread social acceptance and control of a sufficient number of the political levers of power.
In general though it is also not correct to say that the US has complete free-speech absolutism. Actually planning to lynch someone, for example, is not protected free speech. The argument for further restrictions is that those lines may not be correctly drawn by our forefathers - why should actually planning to lynch Tom Brown be illegal, but the KKK rallying to lynch somebody be legal and protected, as long as they don't name a specific name in advance? Why should arguing that people should be lynched in general without the specific intention to do so today be protected? There are many places we could concievably draw the line without really impacting anyone's actual freedoms to do anything other than incite hatred and ultimately inciting violence and death.
You also dodge the central question - Do you believe Hitler had a protected right to free speech worth defending?
I may or may not read your response because I don't believe you're arguing in good faith though.