Because differing opinions are good and necessary for a better world.
You’ve all seen it happen, discussions about matters of opinion turning into heated debates or even more heated shit-flinging contests. Sure, you may be entirely convinced strawberry isn’t the kind of jelly you put on a PBJ sandwich, but if the other guy eats them for breakfast every day, so what? It’s fine to call him on his “bullshit”, but if two sentences in he isn’t convinced yet, then it isn’t worth the effort to continue.
Being able to shrug and say “eh, to each their own” is a very powerful thing. Hell, just take that mentality with you into every discussion about personal beliefs. You’re more open to listen to someone else’s point of view when you’re not busy being on on the defensive or looking for things to attack them on.
Unless, of course, they have the toilet paper roll hanging wrong. Chew them out on that. It matters.