Some people exchange ideas to learn. It's risky since these ideas can sometimes be rejected. We feel bad when that happens but we also feel good when they are approved of. Because of this mechanism, human subjectivity tends towards realism and wisdom.

Others exchange ideas for satisfaction, they bypass this auto-regulating system to maximize "good feelings". Soon, they learn that parroting the majority-opinion will produce happy hormones without the risk of being rejected

So they use this to socialize rather than learn.
This is what I call "opinion borrowers"

The problem here is that they are intellectually incapacitating themselves since they accept conclusive claims without knowing the sustenant precepts or web of ideas that would lead them to this conclusion.

When confronted with reality or arguments, they don't have the necessary precepts or understanding to formulate a reasonned defense so they resort to ad-homs and various fallacies at the measure of their weakness