I never said you couldn't get a decent photograph by moving with a prime (although lets be fair, forensic photographs are hardly known for their artistic merit), just that you wouldn't be able to get the same photo as you would with a zoom by zooming in or out whilst moving; something a lot of people who advocate "zooming with you feet" seem to like to proclaim.
I've never seen this claimed. They may have said you could get a person to be the same size in the viewfinder by doing this.
But the advice to "zoom with your feet" is IMO absolutely NOT about trying to take the exact "same photo". Besides being fundamentally impossible, why would you particularly wish to do this anyway? The aim is to get a BETTER photo in your particular circumstances... rather than, obstinately standing in the same place using some lens which does not accommodate the subject suitably - or, which fails to portray it subjectively as you want - out of self-spite.
I'm not saying you shouldn't move around with a zoom to get the best photo possible, I'm saying that a lot of people assume that that same photo would be possible with a prime if you just walked backwards or forwards a bit which is clearly wrong. A lot of people however claim that this is possible, and that zoom users are lazy and buy a zoom so they never have to move.
Saying so would certainly be both unfair and foolish. I am not sure who IS in fact saying this.
I wonder if you are making too much of the observation often made while expressing a liking for prime lenses, that with primes you physically cannot stand still and zoom. This simply means that these people find it helpful that the equipment's fixed presentation of the subject naturally encourages and reminds them, that they may need to move their viewpoint around, in denying them the option not to do so.
Sometimes people talk about "directness" or "simplicity" in this regard; that is a matter of psychology and personal preference and acquired familiarity. Not of technical or artistic superiority.
Someone else may regard it as more "direct" and "simple" to vary your field of vision by turning a ring, rather than by selecting a different lens out of the bag. And that's an equally valid viewpoint to hold, of course.
Both people are just saying, one or the other approach comes more naturally to THEM.
For a given subject, the type and tactic of pictorial "solution" will generally be different, for different focal lengths. That means moving around, in pursuit of an entirely different end result in each case. And this idea of "zoom with your feet" partly says: no excuses, do whatever is needed using the equipment you have rather than what you wish you had.
I've never heard it used in such a way.
You seem to have latched onto only one usage of this particular cliché.
Analogy: a piece of music tends to be performed differently on different instruments, according to the "musicality" requirements of each one. And that is how using primes is for me - while, I find the zoom lens more analogous to using a synthesiser, which can emulate the sound of many instruments quite well sonically, but which always somehow fails to produce the characteristic results of the real thing, for performance related reasons. I repeat: just talking about my personal experience here.
I guess if you've never had a decent zoom I can understand having that feeling. And one or two very special primes are unequalled.
Sure, people like using particular equipment, because of the shooting experience, and also because of the results they personally get. One person may find that this favourite equipment tends to be prime, another may find that it tends to be zoom. Or a mixture. No biggie.
But IMO you seem to be struggling a bit with, or at least resisting, the idea that someone might sometimes actively PREFER shooting with a fixed focal length, for reasons other than optical quality.
It really can be just that simple. There is no need to bring technical superiority, or tribalism, or aesthetic condescension into it.
Just as: people don't shoot B&W
because they have never experienced "decent" colour.
BTW while the origin of this saying may have come from contrasting zooms and primes to some degree, people aren't ONLY advised to "zoom with their feet" when they are using primes - but with zoom lenses also.
I've never seen that. I've heard of people advising trying different perspectives with the zoom, but why would you "zoom with your feet" when you have a lens to zoom with?
Seriously?
Zooming with your feet IS trying different perspectives... if you are not also changing your focal length while doing do, then the subject gets unavoidably bigger and smaller in the viewfinder as part of that; you are dealing with just a subset of all the framings which you could have had with a variable lens. But a subset of the infinity of all possible pictures, is still an infinity - the whole scene is altering regardless, as well; things are coming into and out of view, changing proportion, etc as well as altering over time, and being presented through the filter of some human being's personal vision.
For instance in your example what if the photographer wanted the subject larger whilst also having more of the scene in? How would that be accomplished with his single focal length?
Not sure I understand your point here - it would be done the same way, regardless of camera or lens. Again, no excuses - take lots of shots and stitch them, if your single lens does not give you a broad enough field in a single shot. In any case, the proportional relation of subject to scene is a working distance / geometry issue, not a lens / optical issue.
How is taking lots of shots and stitching them the same way as zooming out?
Geometrically the same, I meant. If you simply don't have a sufficient wide-angle with you, then it makes no difference whether you
don't have a zoom wide-angle, or you
don't have a prime wide-angle

.
Not to mentioned how hard getting a clean stitch is with large foreground elements. I personally don't carry around a nodal pano head with me, and if you do surely it kinda ruins the simplicity of primes a lot of people claim.
Sure, though incidentally (in pure physical terms), a compact prime can work very nicely on a nodal rig; when lighter, with a shorter distance to entrance pupil, therefore shorter lever arm, demanding less solidity of construction in all the elements. Similarly, I have found it far easier to achieve acceptable hand-held pano results with that (again, in pure physical terms).