What's the point of asking this in a job application?

Because if you've received an appraisal 1-2 months before applying they will use it as an excuse to lowball your salary.

Very curious. The cynic in me wants to agree with MrRobot, but is that it?

+1 curious. Would like to know recruiter or HR view point here

Apart from what @MrRobot1992 said, it could also be to ascertain that company viewed your contributions valuable enough to translate in money.

It is not necessarily a right metric, but could be if same industry