Once, when my partner and I were much younger, she was having a pretty severe panic attack. It took quite a bit what was the source of the intrusive thoughts, but a lot of it was climate anxiety, and eventually she blurted out something about polar bears going extinct.
I told her "Sometimes, you have to let somebody else worry about the polar bears."
The problem with saying "Whataboutism" is simply an antidote to perceived "hypocrisy" is that it ignores the human condition, particularly the aspects of ourselves such as:
a) Limited knowledge
b) Limited energy
c) Limited perspective
d) Limited ability
I may advocate locally for local environmental efforts; this does not make me a hypocrite because I'm not also doing anything to save the polar bears, or the thousands of other environmental issues I could pursue. My particular passion for trans rights and recognition is not negated because I'm not as equally active in combatting biphobia, for example.
By all means, let's get a list together of all the things that we'd like to fix about the currently published D&D 5.0 oeuvre. There's a lot there. But then, that's not really the issue currently up for debate, is it? The topic currently at hand is slavery.
"Whataboutism" seeks to scuttle specific and direct conversations by insisting upon expanding their scope beyond the capability of the group to manage. Which is, more often than not, typically the point.