They are afraid you are going to infect the good works done by the active JWs. Are you aware that "One weak JW who is fading can take out Five strong JWs, so it's best to avoid or greatly limit your contact with weak JWs?" Circuit Overseer (past) words.
Who, who get's Shepherd Calls by their elders, most is done to inviduals who showed more promise than other Witnesses who had sub-par Field Service time. Investment hours of your elders is based on your former productivity, if you were a "Drain-O Witness", don't plan on seeing anyone other than another weak person who actually cared about you.
Why do the "strong Witnesses focus on being around the strong"? The same reason the Pharisees craved the adultation of other Pharisees, unless the Witness are seen doing something by other men and women, it's no fun to perform acts of charity. Blowing the trumphet, if the trumpet is blown you better make sure there are lots of Witnesses who can observe your religion.
Religion is the practice of serving God before mankind, Spirituality is the search of truth, trying to seek more truth without the aid of onlookers. How many times did you hear "The World Can See Us In Field Service", "They know where here even if they don't answer the door!" It's all about "they" and "them", not God and Jesus Christ, "the elders know we were in Field Service or the elders know we are sick" is justification before men, does that make sense? What did the elders do with all the information they collected from you, the elders based your past production on how often to check up on you if your not attending meetings for any period of time. Some elders are so incompetent, they will allow a Pioneer to go off the list, not check up on a former huge "shaker" who tilted their congregation hours big time, they allow this person to fade and never be seen cause they are too lazy!