By your definition of a job being broken, "because the only place they're slightly useful is in Salvage", is wrong. A good PUP (not a gimp one like the majority out there) can keep up to people in most situations. Hell, there were a thread on BG a few months back where a PUP compared his damage to melees, BLMes and SMN's on Kirin. and guess what? He did decent damage. Kept up to them well. Off course a bad PUP will be bad in a party. A bad WAR will be bad in a party though (albeit, probably better then a bad PUP). Just because one person is bad at their job doesn't make everyone bad. PUP happen to be a very technical job where you need to spend a lot of gil to get good equipment, hence why so many suck.
A good PUP can be useful in several places. As an example, on kited NM's. Fortitude, for example. A PUP's Tier 2 spells can do over 700 per nuke fully merited with good equip. Naturally, it won't always do this, since it requires maneuvers. If someone does not have BLM lvled for these situations, a PUP can actually be a good alternative. They're also usefull on Temperance, since they can deal all three damage types, depending on the automaton they use.
Yes, PUP could be leap and bounds better, but so could other jobs be in end-game, considering a few have close to no use there, such as DRG, and apparently you can't see a use for PUP, even though my friend's LS on another server ask her to come PUP.