I'm 1700-1800ish lichess (Crazyhouse and King of the Hill). I agree with this, but with one caveat. I memorize a few openings just because games can get crazy sharp pretty quickly, and there are a few patterns or move orders in the opening to memorize just so you aren't mated quickly.

I don't memorize games several moves deep, just 3-4 maybe 5 depending on the opening, which especially in Crazyhouse as there are only probably 3-4 good openins.