Don’t count on that, with a proper mocap setup making 300 animations is trivial.
The fact you can avoid it and the result is similar doesn’t mean people wont do it.
Or more properly shouldnt do it.
In your case particulalry, swapping from a regular rifle stock to a vertical folding grip wouldn’t necessarily involve much of a pole switch (proper gun handling stance should cover both flat under and a vertical grip).
But imagine extreme cases like holding a spear or a two handed claymore… the Ik becomes effectively useless (and in fact its only really used to adjust from shoulder width differences in characters at runtime, since without it you could potentially not reach the handle).
Either way, different situation but similar solutions.