Pfff quite an update overnight. I am with
@Hartattack on this.
I do agree that agencies do not have legal powers to dictate terms of general diving, hence they do the next best thing: they recommend.
The recommendation is to stay within training limits AND experience. This means both apply. If you need to go to the store for milk and coffee, you missed the point if you only come back with coffee. In the current (Dutch) OWD manual it is even suggested that if during open water training you do not go deeper than say 12 meter, that would be your certification limit. Obviously this is not correct (after checking it turned out to be an awkward translation), but it is an indication to stay on the conservative side. I have never seen any recommendation to build your experience beyond your training standards, only within those standards. This is especially true when validated ways of extending your experience are available, in this case AOWD and deep specialty.
With regards to personal diving, there is no scuba police (in some areas there actually is) and you are responsible for your own diving. Want to go to 300 meter on a single 80 cuft with air? I would strongly advise against it but if you really insist, you have the right to kill yourself. If you want to avoid that, I strongly advise (bloke on the internet, so I cannot dictate / enforce) you stay within your training limits.
However, all this changes if you are a DM. With DM I mean dive professional working in any capacity with students / clients, not "guy who is qualified but is actually on a personal holiday dive in the same ocean now".
As a DM you do need to stick to the training standards, even when guiding. Even if it is legally arguable whether or not you need to stay within training standards, you still should do so being the role model that you are.
In addition, you are supposed to overview the diving activities in a safe, conservative manner. There is simply no way to suggest it is ok to take the clients beyond their limits, while at the same time making safe, conservative decisions.
Now obviously, in the real world, stuff does happen. I have guided OWD divers who dropped below 18 meters. Now the big factor is intent. Did you brief the dive to go to 25 meter or did you brief 18 and was there an unexpected downwards current? If there was an unexpected drop, I would consider it as an incident. In all honesty, I never did go as far as filing an incident report (maybe I should have) but I definitely made sure to address it in the debriefing.
If you planned to go deeper than the limits, you (as a professional) willingly decided to take your clients beyond their limits. Unfortunately we read about stuff like "the dive opp took me to 40 meter on a single 80 even though I am only OWD" all the time, often leading to operator / agency bashing.
The fact that professionals do take clients below their training limits it the very definition of "normalization of deviation".
If you are unfamiliar with the concept, read some of Gareth Lock's work:
The Human Diver - Counter-errorism in Diving - Home Page and watch the "if only" video. "Normalization of deviation" means that when you cross a line, the same line starts to drift. What is unacceptable at first, becomes acceptable or even normal the more you do it. If a client gets taken to 25 meter by a dive professional, it must be ok right? So now it seems to be ok to dive to 25 meter with an OWD certification. 27 meter doesn't seem so much different. Dive after that, maybe 30 meters isn't so different...Suddenly the OWD diver finds himself narced out of his mind at 40 meter, way too deep in the incident pit and everybody shouts "well he should have stayed within his limits"...
Even if you are a DM / instructor / course director / more experienced diver who is simply diving with friends (but in no professional capacity) there is a certain authoritative gradient. I am not talking about legal aspects here, but human behavior. "If somebody who has more experience than me is doing something a certain way, it must be a good idea to do so. After all, they really know what they are talking about." Unfortunately, stuff like this is all to common.
Simple example: when diving with friends, I do not do a buddy check all the time (not even close to be honest). Even though I do know better, complacency steps in.
Now here is the excuse I tell myself: "I am an experienced self reliant diver and I am confident I can handle anything that would be caught by a buddy check. My friends are equally self reliant. And most of all, I have checked my own equipment well before we would even do a buddy check anyway."
Even though this might all be true, at the very least it is setting a bad example, and I am trying to alter my behavior because of it.
Another thing to remember is that a lot of dive professionals are making a lot of hours for very little money. The dive industry, especially on popular tourist destinations, is saturated with people who will work for peanuts. After all, diving is a cool thing to do. Now if you are supporting a hobby, that might be fine, but if you are depending on the income, it becomes really difficult to say no to clients, or to risk the tip.
So breaking the safety rules (sorry; standards) becomes tempting, after all, usually nothing serious happens and hey, the client will be going home next week anyway. Again this contributes to unsafe behavior from the dive professional, but assuming there is no significant visible incident, the client will never know and might consider it normal.
All in all, like
@Hartattack said, I will do my best to always stay withing the most conservative applicable training standards. Stuff might happen, but that would be an incident, not normal behavior and should be addressed as such. If me looking out for your safety is offensive to you so be it.