My view only (duh), but it's one of those terms that seems overused, and a retort when you don't have much else (same as "quit trolling, stop being obtuse, you must be blind if..." etc.).
There's nothing wrong with making a comparison or analogy. I get that comparisons can be made in "bad faith," to distract, threadjack into tangents, etc. But, for example, the threads about whether extreme "left" or "right" is more violent, I see "whataboutism" thrown out way too much and used in a way to try to stop discussion.