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.
It's interesting, when I tell people they need to be prepared for this bar I get a surprising number of people who just don't seem to want to accept that it's true or flat out claim that it's not true when I know they haven't interviewed in years.
In the past 2 years I've done about 40ish+ interviews at all the big tech co's + smaller-midsize startups and aside from 3 or 4 take home assignments I was given, _every_ interview was leetcode style, to the point where I would just start noting which exact leetcode questions I was asked when friends asked about my experience. The only exception would be 1 or 2 "system design" rounds out of the 5/6 on-site interviews if the company was calibrating me for senior level.
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.