I'd disagree. If you play a line like the Englund Gambit, you are going to get trounced.

A lot of times, Memorization isn't even needed. People develop mental shortcuts for calculation in positional, endgame, and middle game sections.

Things like forcing doubled pawns on the C/F files (depending on your color), calculating whether you can promote before the king can catch up (that triangle strategy). Lucena and a few others.

With a solid opening repertoire that's chosen to force certain openings/sublines you can limit the study needed significantly (and shoot to the moon rating wise).