ain't it strange that there's still a big barrier when it comes to putting on an unaccompanied solo singer in a club or on a festival stage

Wouldn't know, MoorleyMan, wouldn't know.

I guess it's partly about pacing and variety. Some of the best headliners I've seen will actually switch instruments once or twice mid-set, which livens things up, and that's quite hard to do if you're not playing an instrument to start with. Again, if you're a guitarist you can use a bit of dreamy picking to cool them down, or some brisk choppy strumming to wake them up - these effects are also hard to replicate on vox humana. But if you were, for example, an unaccompanied singer with a hatful of traditional songs and as many again of your own - including some well-received comedy numbers and a couple of poems - you might think you could manage more than two from the floor.

(Then again, perhaps such a singer ought to stop moaning on that Internet and put himself about a bit more.)