I disagree.
Solo is an outlook as well as a way to dive alone...can't believe how many people don't seem to agree with me on this.
The bungee reg, for example is an absolute for me to dive solo. You fall in knee deep water, alone? Necklace is priceless. etc, etc.
I may not be DIR to DIR divers, but I can outline the ways their philosophy and methods have changed the way I dive for the better. For example, I still use a computer, but I constantly work on trying to estimate my deco status mentally. I favor the DIR gear config and think they have much to offer.
The long hose is very valuable for air shares for me and other "solo" divers photogs, etc. We may dive alone a portion of the drift to get pictures and resume buddy style for the stops and boat pick-up.
There is nothing that says you can't fuse styles and practices...of course conformity and uniformity is a fundamental tenet of DIR, so expect to be challenged. Lots of Catholics use BC too.....
Not a black and white world, for me. You see what works and then apply the MOST important concept which is why, and for what purpose?
This allows you to stay streamlined and reduce your gear to the minimalist, "function follows structure" philosophy and avoid silly purchases.
Very few "solo divers" actually are out there diving alone in my world. Kayak divers are an exception. Most solo divers have an outlook of being ultimately responsible for their own choices and assumption of risk...and their assets are hopefully off the table. Doesn't mean you cannot dive around others and benefit from being able to assist or increase your options with a long hose.