The blog post explains why it's the opposite, not using recursive locks kills two birds with a stone because you know which invariants are enforced at locking b

The blog post explains why it's the opposite, not using recursive locks kills two birds with a stone because you know which invariants are enforced at locking boundaries. Therefore, functions that take the lock know exactly what invariants to expect, those that are called with the lock taken don't. It's the opposite of spaghetti code.