People use extreme comparisons when arguing with others—"You think it's ok to eat cows. Would you think it's ok to eat people?"—because they don't know how to debate. Their minds are so empty of facts, experience, and wisdom, so they resort to childish attacks on others.
They can't seriously come up with points to back up their statements because they know what they're getting into challenges them too much. They'd rather live in an echo chamber because that way, no one will challenge them. They won't have to think too hard.
By allowing themselves to stay in their bubbles, not having to think about their positions and reflect on their opinions, their minds gradually shrink and become only what they perceive to be right. They don't know how to respond to debate. They only know what's right to them.
When everyone around them in their bubbles tells them they're right, they can never be wrong, and that those who disagree/go against their opinions are bigots and _____ists/______phobic, they will think this way, and will follow what they've been instructed to believe.
All I'm saying is that when you're debating with others and all they can come up with are extreme arguments and attacks on points of view back, just know they don't know anything else besides what they've been told to think. And we can't always blame them.
When you're told that what you're doing/saying will ultimately be for the common good of humanity, you will do it, no question. There have been studies done on this. It's quite sad and even terrifying, but it's true. They feel what they're doing is right. But is it?