That *should* be the case, as well as providing general
ground support, ie catching or handing up gear or tools. Of course I (and I'm sure many other people here) have seen footers used to provide
ballast to a ladder that is placed on an angled or otherwise precarious position, or from which a person at the top is leaning out,
etc. It should go without saying that this sort of thing is outside the intended usage of just about every ladder out there, and so should not be done.
That said, you will find places/situations where that's sort of a 'wink,wink, nudge,nudge' rule, and people will do it anyway. In such cases you should know that misusing a ladder presents a very real risk of serious injury, and it's often left up to you to recognize that what other people are doing--or asking you to do--is dangerous, and you would not be in the wrong to
point this out or refuse to take part in it. Doing so may get you into trouble or even cost you work, but your reasonable
safety is more important than a job. And if you *do* get into trouble for refusing to do something that is unreasonably dangerous, you very likely will have legal recourse.