I have to admit I'm having a quiet snigger to myself at the irony of this thread.
Obviously every single one of us started out as a low time pilot.
They may not intend it, but the single-crew advocates come across as saying that when they were low time, they were capable of handling it, but the low time F/O is for some reason not so capable at the same stage of their career.
You can't have it both ways - stick the new F/O in your single-crew job with the same number of hours you had when you started it and I'm sure their learning curve and performance will be the same as yours. Or are you saying you're superior?
Given that, one could argue that it's safer for everyone concerned with the low-houred pilot learning in a multi-crew situation, rather than on his/her own single crew.
If the low-houred single crew pilot can safely do their first ever flight with passengers and not kill anyone, then strange as it may seem, the low houred F/O can probably do the same in the event of an incapacitation.
Now if the quality of all new pilots coming out of training has fallen, then that's a different argument, and will obviously affect both single-crew and airline ops.