I also think 'whataboutism' is critical to maintain logic consistency and try to avoid bias. For instance imagine I dislike group X, and and I use a condemnation of action A (which they engage in) as part of the justification for that dislike. If my condemnation of A is valid and genuine supportive evidence of my rationale for disliking X then A should be bad in contexts other than when X is engaging in it.
And so comparing A when done by actors other than X is absolutely critical in determining whether it's actually indeed a bad action, or whether I'm simply clouded by bias and calling it bad because of my dislike of X.
In searching Google Trends it's somewhat unsurprising to find that 'whataboutism' as a term didn't even really exist until around 2017 [1] when partisan driven bias and antagonism started to exponentially skyrocket. It's quite an insidious term since it helps deflect potentially logical critique of irrational views, but has a paradoxical connotation of legitimacy and intellectual authenticity.
Translation: what about all the countries that aren't as bad as China?
A certain amount of "whataboutism" is unavoidable if you attempt to make any comparative statments, or believe inductive reasoning is possible.