Well I guess he is "described" as a socialist in the same way the sky is "described" as blue. Your question is easy to answer...look at all of human history and around the world right now to see what you get when the far left gets their hands on the levers of power.
One of the more interesting parts of that story is that in that time, the fascists actually tried a takeover of the US government, executing on a plan to sideline the President and replace him with a shadow government.
Fortunately, they failed. They tried to recruit a populist veteran into their ranks who had no particular love for a government that had abused its World War I veterans... But had less love for a bunch of (essentially) early-twentieth-century technocrats that had profited off the sacrifices of the veterans. He refused to keep the conspiracy and blew the lid off it, and his reputation was both public enough and spotless enough that the conspirators couldn't either silence him or tarnish him.
(The conspirators were never prosecuted. One hypothesis as to why is that Roosevelt saw an opportunity and co-opted the plot: some of his New Deal policies were facing pushback and he might have put on the table for the conspirators "You can dodge a treason trial if you just back the new policy with your capital and your political will").
(p.s: I probably shouldn't extrapolate this historical anecdote to the modern era, but this story does give me reason to wonder if a rule like "In the industrial era, massive inequality due to under-regulated capitalism leads to attempts at reform, and those attempts breed counter-reform in the form of fascists and their sycophants formed by those who perceive they have the most to lose in reform..." might hold water).
How do these people relate to Democratic Socialists in the United States of America in the twenty-first century, since that's the political affiliation of the person we're actually talking about?
Taken to its extreme, any system of government is bad. The people you list there have one thing in common and it's not socialism: they were all malignant narcissists. A malignant narcissist in charge of any government -- left or right wing, communist or capitalist -- will create chaos, death, and destruction. Witness now, the American government falling into fascism under the leadership of yet another malignant narcissist. If things keep going this way, the US will suffer the same fate as the USSR. Not because the US fell to socialism, but because it fell to narcissistic authoritarianism.
Mamandi, for his part, is not a malignant narcissist, so New York should probably not turn out like Soviet Russia. The US as a whole on the other hand may not be so lucky.
Surely you understand that the word socialism means a lot of different things to different people?
You argument is that this is "just generally bad"? Or somehow a socialist mayor will be the downfall of western civilization or something? It seems like if his policies are bad, he won't be reelected and you'll have a more succinct example to point to than "all of human history". The great thing about a mayor is that they have very limited ability to impact civil rights, Giuliani notwithstanding.
Well this rather small level of nuanced thinking you are suggesting is never applied to conservatives is it?
So we'll take the same approach with liberals.
What you are saying is effectively dog-whistling in support of Stalinism. And that means you support the killing millions of people.
Clearly you are evil and your career should be destroyed.
