Semaphores are not typed. They is no semantic connection to the thing they protect. Debugging concurrent systems with mutual exclusion enforced through these low-level primitives is a nightmare.

If you forgot to lock/unlock, you'll never know! The compiler cannot check it. Deadlocks are imminent.

We've had better abstractions since the 80s. Conditional critical regions, monitors, and (ideally) protected objects. Hell, even guards are better than semaphores and mutexes - at least they are associated with their critical region!

I struggle to think of situations where a semaphore is the best choice. Maybe in extremely high-performance cases, but even then the compiler can usually make a better decision.