I was gonna say. It's pretty absurd to make the comparison of [n] damage types versus "lol only Diplomacy". As Gentlefish said, in PF you have Appraise, Bluff, Diplomacy, Disguise, Intimidate, Knowledge, Linguistics, Perception, Perform, Sense Motive, and Sleight of Hand as the skills which are likely to come into play in nonviolent encounters, even if we specifically restrict that to conversations with other sapient beings (ignore things like Handle Animal to interact peacefully with sub-sapients, Escape Artist used to remove oneself from a situation after submitting to capture instead of fighting, &c.).
Even if you don't count all the different subsets of Know (X) and Perform (X) as individual skills that's still just under half of the skills in PF which are either dedicated to nonviolent encounters or useful to some degree in the same. As opposed to 7 used as elements of specific types of actions which might be used in combat.
It's also a false equivalency because it assumes that all nonviolent encounters consist of the player saying "I roll Diplomacy," and the DM saying "You pass/fail." That's like acting as if all combat consisted solely of "I roll to hit." "You miss/hit." "There's my damage roll." while lumping every possible way of dealing damage into a single category labeled "ATTACK". If that's how nonviolent encounters play out, either the DM is lazy or the group as a whole just wants to kill things. It's not like there aren't rules for nonviolent encounters, and it's not like they aren't supposed to give equivalent rewards; it's all down to the DM and players choosing not to play that way.