Sure, you can rank as a group but you can also farm observation as a group. And it's not like ranking actually helps social interaction -- you are typically too busy grinding mobs. Whereas when you go sightseeing as a group, you typically talk and it facilitates expressing your character's opinion on the things you see.

Also, farming observation to the limit is trivial and no more difficult than reaching hero rank. And I know I keep looking at things even after I reach the cap, and bring people around on explore trips. It's fun when you put it into perspective.

Rank limits to exploration aren't very intuitive, though, I could do with them being abolished.

Also, when edge bonuses for observation were made 1/3000, I suggested that the obs-exp cap be halved instead, with bonuses staying 1/1500. The maximum effect would be the same, but less of a "grind" for those who don't like doing it.