I think leetcode helped me quite a bit as a software developer. I was in a similar boat as you, 12+ years experience doing software. I have an electrical engineering degree (famous for being bad programmers ha!) but no CS background. I could normally hack at problems, figure things out, and get things done in different settings (Linux, embedded, web, etc).

However.. studying leetcode really helped me understand fundamentals much better. I also read some algorithm books. I feel like I have a better understanding of software in general! And it has helped my career tremendously. Just my experience, I totally understand why people don't like the interview but for me I appreciate how coding problems are at least more straightforward than other arbitrary interviews.