"There are certainly some developers that aren't competent. In my experience those developers get weeded out of the industry relatively quickly."

That gave me a chuckle.

If you define competence as being able to hold down a job..

(Though, of course, some social intelligence goes a long way. No need to actually know how to code.)

They don't get weeded out. They might even sit in one place for years at a time before management catches on and does something, if they even catch on at all. Or, they will bounce from job to job infecting various roles with their poor work until the immune system of each company slowly wakes up and does something about them. Sadly, this gives them more "experience" and industry credibility, making it even easier to trick future victims.

In my experience even something as simple as effort varies greatly between two equally skilled developers and results in very different outcomes.