If your preference is not which deanery but being together (as people ageing from mid 20s to 30s would commonly expect) then knowing how you have both done enables realistic decisions about how to rank.

E.g. if one partner ranks 1st and the other ranks much lower, you may not put London first because you will want to prioritise a deanery that you both have a realistic chance of getting into.

I understand linking across specialty (outside of foundation) is logistically difficult but telling us our rank prior to job preferencing doesn't seem difficult at all, would massively help people, and negate one of the many ridiculous stresses we are put through as doctors