Some people really believe that there are certain things that you should not be allowed to say. That belief is strong enough that there are people being prosecuted for violating laws that ban - but manage to not clearly define - “hate speech.”
But aside from legally defining what a “hate speech” law would forbid, there are two bigger problems with the concept.
First, why should the government be involved with regulating an emotion? I hate the sugar ants that make themselves at home around my kitchen sink every spring. I hate that rats thrive in every city I have ever lived in. I hate the fact that spellcheck wants to force me to “correct” the short version of the word “until”, which only has ONE “L” (“till” is where a business keeps cash). I am pretty sure that when I was in middle school, there were people who hated me.
Second, trying to outlaw hate is as stupid as a law to mandate cheerfulness on a rainy day. No matter how clear the definitions in such legislation, the elimination of a concept cannot be accomplished by restricting language.
I know this because the US government’s attempt to make TV safe for children, pre V-chip - brilliantly satirized by George Carlin in his “7 Dirty Words” bit - was a wellspring of comedic inventiveness during the 1950s-80s. The double entendre never had it so good.
Just the fact that we knew that there were things that they could not say, but that they would use other words or actions or images to communincate, probably even made hilarious some things that, clinically described, might not have been very funny.
Even if there were a law that specified that you could never say the word hate or any synonym of it or any antonym of love, a law that listed every single phrase or word that could be classified as a slur againnst any demographic group living, dead or imaginary, the same ingenuity that 1960s comedians used to turn the anti-naughty-speech rules into prime material would easily be applied to generating expressions of forceful, visceral displeasure with the company, beliefs, practices or opinions of any subgroup of humans it is possible to describe.
Like a stifled laugh in church, or a tight lid on a saucepan, such a law would only be creating a contained, pressurized vessel - such as would be useful for generating an explosion.