I do still think that training materials should better elaborate on that detail. It's obviously often misunderstood.
I believe the unclear writing is intentional.
I had a long discussion with PADI leadership about a similar topic (overhead environments) a couple of years ago. That discussion talked about the fact that PADI is pretty clear about the recommendation that no one go into an overhead environment without proper training. I talked about all the dive centers around the world taking divers through coral swim-throughs and open decks of wrecks. Their reply was that swim-throughs and open decks are not overhead environments--they are open water. Where does it say that? Nowhere. They said they don't have to state it because everyone understands that already. The Hell they do, I responded.
We were talking about the wreck course and the fact that the course says you can never penetrate a wreck without laying line, and that is where they said that passing through an open deck, the wheel hose, etc. is not a penetration--it is a swim-through, and a swim-through is open water. No need to lay line. Everybody knows that, they said.
It became clear to me that they were afraid to put into writing that it is OK to go through a swim through because of a fear that if they did, they might be open to a lawsuit in case something happened. They asked me for new wording, and I suggested some. They liked it and asked if they could use it in the future. I consented. The future turned out to be 6 months ago, when my definition of a swim-through appeared in the PADI professional journal. It is supposed to appear in the next revision of the wreck course as well. It may also appear in the OW course. I'm just guessing now.
Along with my definition of a swim-through, they included my wording for progressing to more challenging dive situations (such as depth) as your abilities grow. I explained that the change in your personal limits depends upon your mature judgment, your ability to assess the increased risk and match your growth through training and experience to those increased risks. Think about that and see why you might like to have vague language--or the opposite. People who want black and white, no-nonsense rules will favor things like OW = 60 feet, AOW = 100 feet, and Deep Diver = 130 feet (which is, BTW, what it says in the OW course). Unfortunately, those black and white rules don't work, and it will always come down to you using your best judgment. If you write black and white rules like that, rules you know everyone is going to ignore, then you will never be at fault for violations. Thus, for them to put my language about using judgment into the professional journal was a major leap for them.
The only place I know of where such language already exists is in the PADI Trimix course. In the last chapter, students are told that when they complete their certification, their new depth limit is 300 feet. There are no courses after that, through, so when they want to go deeper, it will be up to them to use their best judgment to determine if they have developed the skills necessary to do so safely. It is nicely written, and language like that should be in all the courses.
I could think of about five ways to disagree... but I'll take the enlightened view and defend @Efka76's right to never dive below 18 metres. If somebody believes the rule exists, the burden of proof lies with them following it to their hearts' content.
