Oops; you're totally right. I read the datasheet title, and didn't read to the subtitle. In any case, the trick is alive and well with 74HCU logic, good in to the tens of MHz whenever exact gain and distortion don't matter.
> In any case, the trick is alive and well with 74HCU logic, good in to the tens of MHz whenever exact gain and distortion don't matter.
But you don't get the voltage tolerance with 74HCU (6V limit).
This was one of the interesting things about the old 4000 series because they had metal gates and thick oxide--they tended to work from less <1V (probably not for analog, though ...) the whole way to 20V (convenient for 2 9V batteries).
Old 4000 series were also notoriously vulnerable to static discharge, so I suspect that they didn't have much in the way of ESD protection (if any at all).
http://www.ti.com/lit/ds/symlink/cd4009ub-mil.pdf