This is a challenging balance to strike. I used to work with someone who I considered "that guy", but there was no denying that the code ended up better for it, even if it would have been basically fine otherwise. Especially over the long term, those little things can add up.

On the reviewer side, I have sometimes been in the situation where I end up letting something slide because I didn't want to be "that guy". Then I end up reading the code later and needing to fix it.