I agree with you as sometimes the conditions are not conducive to safely keeping buddy teams together. For example when I started diving, one of the usual dive sites was a tailrace below a hydro electric dam. When visibility was good maintaining a buddy team was not a problem. But when conditions were bad with, for example, a 5 kt current and 5 ft visibility, it could be nearly impossible to keep a buddy team together unless the only focus of the dive was staying together - and then what is the point of diving?
Surfacing to regroup was problematic as your speed down river increased once off the bottom and getting together on the surface was often time consuming given eddies, and differences in the speed and direction of the currents encountered by both divers. The end result was often a problem hitting your exit point which could often mean a LONG walk back.
The local divers' solution to the problem was to ignore the agency prohibition against solo diving, start the dive together, have each diver do their own planning and navigation and if separated, proceed solo and meet at the exit point for the ride back up river for another run.
Grabbing a rock in a strong current and in low viz to collect a snagged fishing lure meant instant separation. But I paid for most of my first and second sets of scuba equipment selling lures to fishing guides in the area, so I did primarily solo diving for the first several years I dove.
The opposing point of view however is that divers should not be diving in conditions where buddy teams cannot be maintained and that are by definition unsafe. And there is the related perception that if a separation occurs, one or more of the divers is at fault, irresponsible, unskilled, etc.
The safety argument does not really wash though in my opinion as in the 20 years I have been diving and solo diving the river below that particular dam and in the 30 plus years that other divers have been doing it, there has been only one fatality and that was a result of a diver getting tangled in his dive flag line (another manadatory "safety" requirement). In his case he was not solo, but his buddy was unable to get back upstream against the current to assist anyway.