I'm 73, I hate only certain gun makes; I hate no calibers. I prefer a .40 or a 9mm since that is what I have basically carried my entire life; other than early in the Army a .45; but found, through personal experience, a 9mm will do the job and so will the .40.
Many people hate many thing for no apparent reasons, other than they just hate them.
Cannot even count how many people I have met in many states and countries who hate a particular caliber and have never used them in a situation where a gun was used to save a life. They get their info from the internet, or friends or grandpa. But it's their right. And I will always say carry what you want so long as it is legal.
And I don't care if a person is carrying a RPG if they don't hit what they are aiming for, size matters not! (However, closeness does matter more than size at times.
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Similar to people who hate certain trucks just cause it is cool. Ask them, why and they have no particular reason.