Prattling is defined as uttering foolishly.
Since prattling is uttering foolishly it sounds foolish
and therefore makes the person that is prattling sound foolish.
Even an intelligent person who prattles could be assumed to be a fool.
Prattling also annoys those who are around to hear it because no one
wants to listen to foolish people or people who talk foolishly. Sometimes
prattling could become a habit, a bad habit. This could especially
affect the people who have to live and listen to the prattler every day.
Therefore, in order to avoid forming this habit one should not start in
the first place like with any habit.