Well, there is often controversy about whether scuba should be termed a "sport" . . . but I believe it has quite a bit in common with other sports, in that proficient technique makes it more fun, and proficiency is only obtained with practice. Anybody can learn the rules of tennis, and pick up a racquet, but beginners spend quite a lot of time chasing missed balls
Perfect control in the water, and sharp situational awareness, are things that come with time and being able to relegate the basic functions of diving to the subconscious level. Just as when we learn to drive, in the beginning, the new diver is managing far too many things at a conscious level, and we all only have so much bandwidth. As the gear becomes familiar, breathing settles down, and kicking technique improves, there is far more brainpower available to be a more attentive buddy, and to refine technique. In this sense, the OW certification is definitely a "license to learn".
Where things get much more interesting is when you try to define the level of proficiency that someone with a "license to learn" ought to have. I know that I have a vision of what I want our students to be able to do, and to look like, when they finish their class. Some can reach that, and some cannot do it in the time available. (And becoming proficient in 45 degree water and ten feet of viz is much harder for people, I think!) And then one has to ask whether to accept a lower proficiency from students for a "pass", or to extend classes beyond what most people are willing to do, in order to bring everyone up to the vision. NW Grateful Diver just put a post on another thread on this topic, observing that, when he worked for a shop that did that, they taught very few students. If you tell people up front, "This class will be longer and more expensive," they go elsewhere -- I know I would have, as an OW student. If you tell them at the end of their 4th OW dive, "You need more work," they just get mad -- especially because, if the extra time is not built into the original class, they will end up paying more than they expected.
Overall, scuba is almost amazingly safe, given that you are spending time underwater. So most of our "licensees" aren't killing themselves, even if they may be driving 45 mph in the fast lane with their right turn signal on . . .