well i think it's important that we differentiate between the two types of "they" we often use on these boards:
1 - just coming back from the bathroom, John finds that half his friends have gone out to get some pizza "where did they go?", he asks to the rest.
2 - They want you to be as productive as possible until you're 70.
the first case is just the regular way of referring to a group of people in third person. nothing much out of the ordinary with that (i guess).
the second case, and i agree with vex here, often used when people are too lazy to find out what's really going on. though if you just want to make a point, it can be very useful to take a shortcut like that.
though in such cases i think it would be a bit more useful to word your statement in terms of he Machine or something, if you want to speak as They/Them as some actual anonymous entity, just to make it obvious that you couldn't point out who "They" are, but that They are made up of the sum of stupidity of humanity or some other emergent property of our race.