> Is it so bad to just click to increment the emoji regardless of the color/tone choice made by the first reaction?

This is sort of what I feel like the parent was implying without outright saying it, too. But: that's not how Slack works. If the only reaction is an emoji of skin tone A (let's say its a dark skin toned thumbs up), and I click that dark skin toned thumbs up to also react, Slack adds a thumbs up with the skin tone configured in the user's settings (which I believe defaults to no skin tone), not the skin tone of the initial reaction.

Settings → Messages & media → Default Skin Tone

There's a big difference between "I wish Slack didn't have optional skin colors" vs "I wish Slack didn't have mandatory segregation"

iirc Slack will remember your chosen skin tone and will increment it based on that, rather than the first colour chosen