The Same Coin?

Why do the Friar and the Summoner tell each other's tales?
Obviously to expose the other's faults. The Friar tells a tale about a deceitful Summoner who extorts money from the innocent and the Summoner tells a tale about a deceitful Friar who takes money for prayers, which, it is implied is virtually the same thing just self-righteously executed. The Summoner preaches in his text and says of friars, "That specially oure sweete Lord Jhesus/Spak this by freres, whan he seyde thus/`Blessed be they that povere in spirit been.' He goes on to describe a Friar who is sent to assuage a sick man of his ire for the church and the Friar. Quickly we see the sick man thinks the Friar is a manipulative liar who uses people for his well being. And unfortunately for the Friar, the other lord he visits to seek some kind of revenge on the sick man also thinks he is duplicitous or else he wouldn't mock him so openly in his house.

The Friar makes a point to tell the group that he would have told them tales of the saints which would have made their hearts wrench with compassion and awe of their committment (something like that) but - we assume - he thought it best to put the fear of god into them rather than the love of god. Does this prove the Summoner's point that the Friar is "povere in spirit been"? The interplay of the two characters and their tales show shared traits which manifest differently, perhaps more violently in one (Summoner) and more insidiously in the other (Friar).