I would blame Marx, Lenin and Stalin for the assumption that socialism implies dictatorship. Socialism already existed in the times of Marx. He did not invent it. What Marx did was “invent” a strain of socialism called communism.
Socialism at the time of Marx was what we may call democratic socialism or market socialism today. Marx called it Utopian Socialism. These socialists were trying to introduce socialism through gradual reforms within the capitalist system. They did in fact have many successes. The German chancellor Otto von Bismarck, feeling the pressure from these socialists, ended up cooperating with them to implement the worlds first welfare system in Germany. It included things such as unemployment benefits and pensions.
Marx however was a radical. He did not believe in gradual reforms. He did not think it would ever work. He may have had the same goal as other socialists, but he proposed a radically different method: A violent revolution to overthrow the establishment. It was this willingness to use violence which is what distinguished communism from other strains of socialism. Keep in mind this is a gross simplification of Marxism which does not do Marx justice entirely, but he was certainly not speaking out against using violent means.
However many socialists did not agree with this. Those socialists who wanted to achieve socialism through democratic means started calling themselves social democrats to distinguish themselves from Karl Marx’s communism. What is extremely difficult when discussing any of this however and which leads to a lot of confusion if you try to read about socialism, is that the meaning of various terms tend to change and get redefined.
Lenin e.g. provided an entirely different definition of communism. He deemed socialism an intermediate system on the path to communism, which he deemed the ultimate system. In Lenin’s view communism was a stateless system. A sort of anarchist system made up of lots of self governing independent communities. Personally I think this definition is more confusing than helpful. I think it makes more sense to think of communists as socialists who are willing to engage in violence to reach their goals.
The second confusion is the word “social democrat.” Social democrats were originally working towards full socialism within a democratic system. However that is close in meaning to what we call democratic socialism today. A guy like Bernie Sanders would most likely have called himself a social democrat up to perhaps the 1970s.
I don’t know the full history but at least in my native Norway, social democrats started abandoning the push for full socialism around the early 1980s. Social democracy began to mean capitalist system with extensive welfare services.
Keep this in mind when discussing socialism with people. They might mean something entirely different from you because there is simply a lot of disagreement on how various forms of socialism should be defined and characterized.