I am not sure that banning of Mein Kampf has a long-term benefit. If it has not been banned it would likely fade into obscurity instead of becoming a symbol.
As a counter-datapoint I grew up in a country that effectively banned religion. One could go to prison for selling a Bible -- subversive literature, yada yada. It worked for a while, but you cannot completely cut the flow of information from the world outside; so sooner or later people who did not have a strong opinion either way see such bans as unquestionably evil. And very soon after that the majority believes that the main reason for such bans is the inability to argue against the banned literature on merits.
I suspect that instead of letting the subject fade into obscurity such bans often provide the best advertising the topic can get. My 2c.
As a counter-datapoint I grew up in a country that effectively banned religion. One could go to prison for selling a Bible -- subversive literature, yada yada. It worked for a while, but you cannot completely cut the flow of information from the world outside; so sooner or later people who did not have a strong opinion either way see such bans as unquestionably evil. And very soon after that the majority believes that the main reason for such bans is the inability to argue against the banned literature on merits.
I suspect that instead of letting the subject fade into obscurity such bans often provide the best advertising the topic can get. My 2c.