When I started doing multi-threaded programming a number of years ago there really wasn't any confusion about this, parallelism, concurrency, preemption and con

When I started doing multi-threaded programming a number of years ago there really wasn't any confusion about this, parallelism, concurrency, preemption and contention were just some of the basic terms you had to learn. Why is there so much more confusion now that we have "better" tools?