Being a good programmer doesn't necessarily mean you're good at leetcode and just need to brush up. I don't meet almost anyone who uses DP in their daily life but you can bet your ass you'll run into a problem that requires DP in a FAANG interview. And you better put it on the board in under 20 minutes or you're getting passed for the next guy who did 1000+ problems as their prep. It wouldn't be so bad if being a good programmer was sufficient and you just needed a little bit of brushing up - but the arms race started years ago... So, now the bar is very high.
Leetcode is solving small problems, often with tricks, in a very short period of time. Being a software engineer is solving large problems over large periods of time.