“A better and more powerful”
When it comes to Divrei Torah and jokes, people have a strong urge to upend. “Oh, I heard it better…”. “I have a better Pshat”, or twist your nose as the person gives you a Terutz.
A person collected his thoughts, organized his point, planned his delivery, and finally shared what was in his mind for much more than the time it took you to listen. He was convinced enough of its value and enjoyed it enough until he allowed it to burst forth. More importantly, if it is his own thought, he takes pride in it and identifies with it.
To knock it down faster than it took to recite it, is to show that what he thought about for a week doesn’t stand up to your split-second sense of truth.
How often I’ve seen the initial reaction being that disapproving twitch, only to be followed by ‘hmm, could be’, and eventually an agreement.
Think about this. This is basic Midos Tovos.