A friend who works at Facebook was telling me recently that since he gets judged explicitly on the code review count, he feels like he needs to immediately drop everything when a code review comes in so he can get to it before someone else approves and it gets merged. As you might expect, he finds that very disruptive.
Since junior engineers and new hires are not yet able to review code effectively, senior engineers end up reviewing a lot more code than they write.
I think recognizing and rewarding this behavior in performance reviews is entirely reasonable for any tech company that wants a sustainable codebase.
I'll just add that nowhere I've worked has counted code reviews in this way and they still get done, so it's not a disaster when you don't officially penalize people for their review count.