Sakura's inadequacy is only in real life, not in-series. she's tsunade's assistant and successor, after all.
in the real world, we see her and scoff wow, she's terrible"
but in the sexist world kishimoto's created, people look at her and say "wow, for a girlie, she's pretty good. i didn't know women could be even marginally competent and hover around average in combat ability. sakura's totally broken through my expectations of what vagina-havers can really do!"