The distinct barbershop sound comes from a bunch of different things, but I've never heard counterpoint named as one of them, I must be missing something. There is occasional jazz or swing timing which might cause a contrapuntal effect.

There is a pyramidal 'coning' structure where the top line is lighter and only leads at dramatic moments, the second line carries the melody but does not dominate, and the two lower voices are extremely full in comparison. It may be this volume balance, completely different from SATB, that annoys Dazbo.

There are definitely chords typically used a lot like 7ths, and chords avoided, 6ths, and if you're used to singing different chords, harmonizing won't come easily at first.

Our familiar verse chorus A-B structure in folk music is not used, they prefer more varied, driving ones like A-B-C-D-A. They like to go as far around the circle of fifths as they can instead of using the 3 chords God gave us to maximum use.

I was surprised at the interesting answers as to why people hate this stuff (and like it when they stumble on it, kind of like how everybody loves Dixieland but nobody buys the albums), so thanks, it makes me more aware.

I wanted to protest that it's not meaningless or phony except in the wrong hands, but I can see where in comparison to other genres it would come off that way.   I have noticed an annoying tendency of bbshop arrangers to glom onto creepy 50s pop songs instead of more worthy older and newer and better songs to hang arrangements on. I hope this trend will reverse as Letterman-free generations start knocking out more arrangements.