Because firing people (and hiring them) is expensive, so companies are risk-averse. Combine that with many people who can talk a good game but can't actually build stuff and we get the current system we have today.

I've interviewed many senior engineers who can't code, and worked with principal engineers who can't design/lead. It's painful and hurts the whole group.

The solution is to make the process of hiring/firing "cheaper" so that companies are willing to take more risk, but I've not seen a process yet that is fair to the candidates.

If we had UBI, it would help a lot - people could quit jobs that suck, and companies could more easily hire/fire people without destroying their lives.