At least at Google I don't think that was their original intent - the idea was to provide a way for employees to express their gratitude away from the perf context.
I don't think they should be used for perf as they are not intended to be objective feedback.
Is the goal of using something like this to help people show more gratitude or is it for performance feedback?
And can those two things coexist or do they conflict with each other?
Would love to hear your thoughts.