Thing is, this is a general response to virtually any criticism whatsoever. And it’s often true! But it’s not always a terribly useful response. Sometimes it’s better to make explicit that bit of context, or that elided step.
True! This observation does not absolve us of our eternal vigilance.
Moreover it’s also a good thing to remember about the other guy’s argument next time you think his conclusions obviously do not follow from his (explicitly stated) premises—that is, next time you see what looks to you to be an invalid argument, it may not be even if strictly on a formal level it is, precisely because you are not necessarily seeing everything the other guy is seeing.
So, it’s not just about substitutions. It’s a general point.
True! This observation does not absolve us of our eternal vigilance.
Emphatically agreed.