Actually no, this is not true.

The guy with 30k atk/nin and 0 critical/injury always land more damage than the guy that have 15k atk/nin and 15k critical/injury. it's just that costs way less to reach 15k injury/crit once you own 15k atk/nin than to reach 30k atk/nin.

That said, suggesting to go for elemental resistances when is more than 1 year that +3 and +4 ceased to be available in game is a very bad tip. +2 are in no way better than +50/60 resistance or than +60/70 damage reduction, because they are situational and getting +20% in all of them right now has a too high price to pay to be worth it (and then appears the hokage minato burst team or the eight inner gates lee blitz and flat out own you).