The fact that it has not been extensively studied does not mean it is logical to dismiss the data we do have, their data was collected with the correct equipment to do so and it seems that the procedures they used are valid. Using that same dismissive logic this statement is true "The safety of Cannabis has not been extensively studied" and we would have to believe cannabis is not safe.
I understand what you are saying. I have consumed cannabis in many different ways for so long now that I should see something going on if there was anything significant going on. I guess I am just the sort who waits until the train reaches the station before I jump off.
My guess is that it has something to do with the amount of terpenes present and the temps at which it is heated which result in the benzene being a product of degradation. We do not have long term data on large groups of people using dabs and specifically dabs with added terps to say with any accuracy whether it is safe or not, all we know is that the benzene rearrangement was most definitely observed at dab temps in this experiment.
Not to take away from anything you said, as an asthmatic, vaping or dabbing rosin seems to be the most therapeutic form of cannabis inhalation for me so far. I find bho/qwiso/acetone extractions can be more "terpy" but are harsh on lungs and throat in comparison to rosin.