Really? That's what's got your knickers in a knot? I have some stable guitars and some that slide out of tune a little easier. When I'm playing with someone else I want to stay in tune so the harmonies are crisp. I've had a guitar go out of tune in the middle of a song, temperature, humidity, tuners aren't tight, string wasn't installed quite right or wasn't stretched, who knows why. It's easier and less painful for the audience to just turn that tuner on and tweak the offending string. Worry about something more earth shattering, like why some people play Elk River Blues in 4/4 all the way through.