How do you prove to the next company that you won't leave? You really can't. You can easily prove you've been working on leetcode problems. If they don't want to hire people with short stays, you can't really fix that. If they don't want to hire people who haven't practiced leetcode, you can fix that. So to an employer, does it really matter if you are good at leetcode if they feel you won't stay around long? So the tenure takes precedence.

Some companies won't care, but finding those is just about as easy as finding a company that's a good fit before you've worked there.