That's because most of the pick up group do easyyyyyy stuff like SR, ambuscade or T1.
If you do harder content is totally other story, I've never seen endgame LS recruit jobs without JP, at bare minimum WHM may be acceptable without JP, even then I think bar spell category should have JP at least.
Personally I never bring jobs to content lv 150+ without JP either, the performance just couldn't keep up and it makes everyone in the pt life hard.