Why is "selection" a dirty word?

A thread on the TES website has the title "Why is 'selection' a dirty word." This kind of formulation, "why is profit a dirty word" or "it's not racist to hate black people" is becoming increasingly common with the Daily Telegraph readership and it bespeaks a certain whining tone. "Oh everybody picks on me because of my sensible right-wing views. It's not fair....etc"

One aspect of the inefficiency of the 11+ is the fact that there is a lot of change on the borderline between the ages of 11 and 16. If you use a test to sort the metaphorical sheep from the goats at age 11 then about tenpercent of your sheep will be with the goats, so to speak.

Another is that intelligence testing itself is a flawed and questionable method with ethnic and class bias built into it.

And another is that whatever method of selection you use, I do not envisage teachers queueing up to teach in Secondary Modern or equivalent schools. Do they Daily Telegraph readers want Grammar schools back so you can work in a secondary modern school or so that their children can go to one? Or is it because they think working in a grammar school might be nice and perhaps their children might benefit from a grammar school education?