I've actually found the opposite.
The people I know who solo dive regularly are much more stringent in doing checks and things, and also seem to be more situationally aware when I am diving with them. Actually my cave buddy prefers solo diving (though we buddy dive in the caves) and he's tied in equal place for best buddy I have ever had. Maybe I've been lucky... but these days I rarely have bad buddies.
I love solo diving myself, much more so than buddy diving in nearly all situations but I don't do it because I feel it is safer (given I have good buddies I would say my solo diving is more risky) but because I like being alone in the water. I wouldn't set up my gear in a way that made air sharing difficult even when diving alone because I've gained buddies underwater before... (in OW).