Consider the monitored approach case, where the PF may not actually do the landing, because the monitoring pilot takes control when visual. It's just semantics - the idea is you must have done three take-offs and landings within the 90 days (or whatever period you have approved) regardless of which seat you are in and what your role is.
Ditto for instructors; the intent is that they actually do three take-offs and landings. I can't imagine any operations manual or rule that would allow otherwise for such a critical role.