I can see both points of view. On the one hand, there are divers who should not go in the water by themselves and others who's skills are so poor they should only go in the water with a DM or instructor. Not warning divers like that of the possible dangers of solo diving would be irresponsible.
On the other hand, there are often double fatalities where one minimally competent diver gets lulled into situations he or she can't handle due to the illusion of the safety implied by the buddy system and a fatality results when the buddy fails to save the diver and even worse a double fatality can occur when the buddy dies in the attempt to save the buddy - often because the buddy is heavily indoctrinated in the "never leave your buddy" mindset and stays to help long after they shoudl have written their buddy of and focused on saving their own life.
The buddy system is, to put it bluntly, far less than perfect - not surprising when you consider it was an out growth of a Red cross swimming program, never really intended for scuba diving.
Consequently, I think a middle of the road approach is more appropriate. Preach the benefits and advantages of the buddy team, but train each diver to the degree needed to ensure they have the skills needed to get themselves out of trouble and to the surface safely - as is the case in a solo class. In fact the agency promoting solo diving does so with the understanding that even if you always dive witha buddy you will eventually get separated and solo skills will ensure that event does not result in any undue risk.
It will however never happen on a wide spread basis as dive training agencies would have to undo 20 years of damage that occurred when they dumbed down OW courses to the point that many newly minted OW divers should not be diving at all unless a DM is present. And a DM dependent diver is not a solo diving candidate.
Short of that, they at least need to stop scaring the hell out of everyone with the "oh my god you dive solo you are gonna die!" rhetoric.
And I do have to say that I'd rather;
1. Dive with a good buddy
2. Dive solo
3. Not dive at all, and
4. Dive with a bad buddy,
pretty much in that order as a bad buddy poses a far greater risk than competent solo diving.