Every authoritarian measure instituted by Eastern Bloc countries was justified by the authorities as a necessary precaution against reactionaries/fascists. The Nazis similarly justified every act of inhumanity as a necessary preventative measure against the takeover of their country by the "Judeo-Bolshevism" of the murderous Soviet regime. The Road to Hell is paved with good intentions.

>Hitler was given power according to the normal process, even though it should have already been obvious to everyone involved that it was a bad idea, because the most important thing is to follow the process, no matter where it leads)

Hitler’s rise was not a product of strict adherence to democratic norms. The Weimar authorities repeatedly broke with "normal process" including banning him from public speaking, suppressing Nazi media, outlawing the SA, relying on emergency decrees, and bypassing parliamentary governance. These anti-democratic measures not only failed to stop Hitler but eroded trust in democracy itself, creating the conditions for his eventual ascent.

Moreover, the KPD (the German Communist Party) played a significant role in destabilizing the Republic. They engaged in widespread political violence, targeting both Nazis and moderate leftists. They fractured anti-Nazi opposition by labelling the SPD as "social fascists" unworthy of cooperating with. The Nazi's Sturmabteilung was hardened primarily in response to KPD attacks through the Rotfrontkämpferbund (attacks that the authorities refused to prevent).

The left's infighting, combined with its own undemocratic tactics, significantly weakened any systemic resistance to fascism and helped paved the road Hitler later marched down.

January 6th was not a normal process and neither was The Beer Hall Putsch. It rhymes.

Neither one put fascists in power. Both ones were elected.

> not as in "liberty" or "liberal world order" - political labels are weird

No, the core of the beef between leftists and liberals is over "liberty," or something that a liberal would call liberty and a leftist would not. Namely, property rights over financial assets. Liberals see these as a kind of liberty: "you own a farm, property rights over the farm connect the labor you do in upkeep and planting to the rewards you reap at harvest." Leftists argue that this might be a nice but temporary side effect and that the core purpose of financial assets is to ensure that rich people get paid for being rich in proportion to how rich they are, thereby establishing, reinforcing, and perpetuating a class hierarchy where the people on the bottom must constantly pay to exist while the people on top constantly get paid to exist. They would tell a different story: "Bill Gates owns the farmland, you do all the work, you pay him everything he asks for, and if it's not enough he replaces you." In turn, the liberal would contend that market competition keeps this in check and the leftist would contend that ever concentrating capital interests ensure robust competition on the bottom and absent competition on the top, slowly crushing any market competition favorable to the farmer. At this point, if it hasn't happened already, the liberal will start lobbing horrific tales of leftists abusing farmers and the leftist will start lobbing horrific tales of property rights being used to abuse farmers and the conversation descends into "whose atrocities are bigger / worse / more relevant" discourse.

If you haven't seen this kind of infighting, it's not because the philosophical rift doesn't exist, it's because actual leftism has been outside the Overton window of popular discourse in the United States for the last 50-70 years. McCarthy's Red Scare was the first push, dissolution of the New Deal Coalition was the last. Class Warfare rhetoric was frowned upon by the liberal + conservative majority and kept out of polite company. Now that populism is back in fashion, leftists have been looking to change that, but they have been having less success than the populist right. Watch this space, though.