I find it really hard to justify that there are dive professionals (the vast majority of them, in fact) who aren't deco trained.
We all remember our early training where we were taught that the ocean simply ends at 130' deep. And, what's more, if you violate your No Deco Limits, by so much as a minute, then you are possibly, probably, almost definitely going to get The Bends and die. Or possibly just spontaneously combust.
Which is obviously nonsense.
But it continues to be the way that so very many dive professionals talk about things, with DMs and boat crews treating NDLs as enchanted numbers, and instructors continuing to pass along this way of thinking about things. Instilling such a fear of these theoretical limits that I've seen people bolt up dozens of feet in the water as fast as they can swim it to escape the scary zero their computer is telling them. Such a rapid ascent introducing a far greater risk of decompression stress than the diminishing NDL.
How much more valuable would it be if mentors and guides and boat crew had a healthy respect and understanding of the theories and safe practices of decompression? Even if they never intend to undertake planned, staged deco dives again in their lives after training... at least they'd be much more equipped to speak about and act on these things from a position of knowledge instead of repeated, misleading dogma.
How much safer would such a dive pro be in a situation where they were looking after someone who went a little too deep or stayed a little too long and was intellectually and emotionally equipped to deal with the easy few minutes of deco to get this person out of the water safe and sound. How much more comforted would that diver be as they asked, in a near-panic at having violated the magic numbers, "Do I need to call DAN?" by someone who could calmly and soberly explain what just happened and debrief the now-mitigated lapse in judgement.
The flip side of that coin: Maybe, just maybe, if DMs in blue holes around the world have actually been trained to make dives to 150' safely, with the right skills and equipment, respecting the environment with significantly elevated risk, they'd be less likely to tell a boat full of Advanced Open Water divers, "We're just going to duck down to 150 for just a minute. It's cool. We do this all the time."
Of course I've got to admit that the additional gear and training is expensive. And access to quality instruction at this level can be a challenge. Especially when you're talking about a 20 year-old DM who just moved to some island somewhere to make next-to-no money as a diver for a few years before growing up and getting a real job.
But in my rare moments of idealism I dare to dream of a better world.
Get deco trained. If you're a dive professional DEFINITELY get deco trained. Just because you've got the training doesn't mean you HAVE to do all your dives as deco dives. You don't ever have to do any deco dives, the scuba police are not going to raid your house and confiscate all your gear; dive however you want. And if that's the case, think of such training as just another tool in your save-a-dive kit.