I apologize then, but the post I was replying to seemed to imply (to me at least) that most adjuncts can continue a research effort and move into higher positions.

I wanted to be clear- that 1. adjuncts generally have no more access to research resources than janitors do. This makes maintaining an active research effort impossible in most disciplines.
2. Unlike postdocs, lecture positions,etc adjuncts are explicitly not career positions- on top of no opportunity to research, the university expects the position is not your primary job.

This doesn't imply that people hired as adjuncts have no desire for upward mobility.

For most adjuncts (myself sometimes included), adjuncting is not their primary job- this does imply they don't have much desire for upward mobility within academia.