In 1986, mimeograph machines were (for the most part) replaced by digital copiers in elementary schools. Those of us teachers who experienced using mimeograph machines will forever remember the distinct smell of the still_damp, purple_ink worksheets that we handed out to our students _ by the ream full. (If you're like me, you can remember that smell right now!)
So what is the concern? There are three big concerns, actually. Our teacher "caution light" should start blinking if we are using lower_level_thinking worksheets (Example: "Check the box next to the correct answer."), if we are using too many worksheets or if we are using worksheets as classroom busy work.