Right, and perhaps it's a poor example. That was, in fact, the first counterargument that I thought of when I wrote that comment. I was trying to think of something that would be intuitive for the audience here, and perhaps in pursuing that goal I made a poor analogy.

The point is, ASL must be a language first, and an aid for the disabled second. On that point, it fails. The goal of a language is to enable communication; if less than 1% of people you are likely to interact with are capable of communicating in that language then it is of limited utility. People who have normal hearing are generally not going to learn ASL, as the value proposition just isn't strong enough. Because of that, even people who have hearing problems might not be incentivized to learn it, for the same reason: it just might not be that useful.

Now, as with any group, a shared language leads to shared culture and a sense of belonging. That, in and of itself, will make ASL attractive to many people. That's fine. It fails at its intended use as a primary means of communication however, as it just doesn't let you communicate with that many people. This, I think, is why many deaf people also learn to lipread: it allows for communication outside of the (relatively) small deaf community.