Well maybe.
Back in the day, everyone I knew who dove, were fewer in number but dove a lot (as in on an almost weekly basis with multiple dives per day/week and probably had a lot more dives per year on average than the average diver now.
My understanding is that today we have a large number of divers who become certified but perhaps only 20% of those divers stay involved in diving after being certified. Of these, many divers only dive during one or two trips per year with a total of perhaps 6 to 10 dives per year - a 3 day weekend's worth for an active 1970's diver.
So even if we have 20, 30 or 50 times more certified divers and many more destination divers now than 30 or 40 years ago, it does not automatically mean we have more dives per year or more diver hours underwater per year - which are far better ways to measure risk exposure than the number of certified divers.
Also, the types of diving differ.
Technical diving accident and training trends scare me a bit as many new technically oriented divers seem to have fairly low levels of life time dive experience - justified by the arguments that training standards are adequate and that recreational experience does not really help in techncial situations. I don't completly buy either argument as, tech or rec, there are good and bad instructors and that means far more than the particular curriculuum or course standards, and comfort and ability in the water as well as gross experience with different conditions can still be useful transitioning from rec to tech.
What training in excess of experience and seasoning can produce is over confidence and complacency that can result in divers getting into situations where their limited skills and experience can no longer get them pout of safely regardless of training. The same thing happens to pilots who are statistically most likely to die between 220-250 hours (when they normally get a commercial license and think they know how to fly and are clueless of many of the creative ways to die) and 2000 hours (when they get their ATP and have learned enough to know there is a whole lot they will always need to learn and they know about a whole lot more things that can kill them.)
In contrast, recreational training has been watered down in the last 20 years to the point that a diver no longer has to be very fit, a very accomplished swimmer, or particularly knowledgeable about math and physics to get certified. They are however in effect often very DM dependent - not something you saw at all 20-25 years ago. This I think has also fed the trend toward more dive boat operators as more and more divers dive solely on destination trips babysat by a DM.
So whether the dive industry is safer cannot be answered soley on accident numbers. It is also a distinctly different question than whether the average diver is "safer". Finally, the reasons why diving is "safer" (or not) are potentially very complex in a system where at one extreme techncial divers of varying experience but comparatively high levels of training engage in much more dangerous activity than the average rec diver, while at the other large numbers of rec divers with little training, experience or currency are kept alive by DM's and dive boat procedures designed to keep them out of trouble from poor planning, limited skills, etc.
I won't even get into rebreathers other than to say they have been around longer than open ciircuit suba. And that now, as was the case then, dive per dive, they kill a lot more divers than open circuit SCUBA.
