Revised Common Lectionary Strikes Out Again

In this Sunday's reading from Mark 7:1-8,14-15,21-23 once again we see the Revised Common Lectionary (RCL) delete some of Jesus' words. I have put them back in (the red letter verses), 

Now when the Pharisees and some of the scribes who had come from Jerusalem gathered around him, they noticed that some of his disciples were eating with defiled hands, that is, without washing them. (For the Pharisees, and all the Jews, do not eat unless they thoroughly wash their hands, thus observing the tradition of the elders; and they do not eat anything from the market unless they wash it; and there are also many other traditions that they observe, the washing of cups, pots, and bronze kettles.) So the Pharisees and the scribes asked him, ‘Why do your disciples not live according to the tradition of the elders, but eat with defiled hands?’ He said to them, ‘Isaiah prophesied rightly about you hypocrites, as it is written,

“This people honours me with their lips,

   but their hearts are far from me;

 in vain do they worship me,

   teaching human precepts as doctrines.”

You abandon the commandment of God and hold to human tradition.’

9 And he said to them, “You have a fine way of rejecting the commandment of God in order to establish your tradition! 10 For Moses said, ‘Honor your father and your mother’; and, ‘Whoever reviles father or mother must surely die.’ 11 But you say, ‘If a man tells his father or his mother, “Whatever you would have gained from me is Corban”’ (that is, given to God)— 12 then you no longer permit him to do anything for his father or mother, 13 thus making void the word of God by your tradition that you have handed down. And many such things you do.”

Then he called the crowd again and said to them, ‘Listen to me, all of you, and understand: 15there is nothing outside a person that by going in can defile, but the things that come out are what defile.’ 

17 And when he had entered the house and left the people, his disciples asked him about the parable. 18 And he said to them, “Then are you also without understanding? Do you not see that whatever goes into a person from outside cannot defile him, 19 since it enters not his heart but his stomach, and is expelled?” (Thus he declared all foods clean.) 20 And he said, “What comes out of a person is what defiles him.

For it is from within, from the human heart, that evil intentions come: fornication, theft, murder, adultery, avarice, wickedness, deceit, licentiousness, envy, slander, pride, folly. All these evil things come from within, and they defile a person.’

Why do the makers of the RCL take it upon themselves to re-write the Gospel? 

In many cases it is to avoid offending people. 

Perhaps in this instance, Jesus' reference to human excrement might be something Sunday pewsitters shouldn't hear. 

In other cases, I just don't get it.