Whenever I watch Billy Cobham grooving, I think to myself "Man I wish I had a dominant left hand!"
Save for electric guitars/basses. McCartney played a lefty Hofner bass and he was fortunate to have one. I believe he even stated that Hofners actually made a left handed bass. Fender didn't for years.Seriously, though, being left-handed can be a serious pain, especially for an instrument like the drums where the pieces need to be configured in a certain way.
Many Lefty-play-righty guitarists are broken. And you're right. The broken ones need to switch back. But when it works, it really works. There was a list somewhere a while back, I'll see if I can dig it up. Here's a thread with a partial list.I have heard lefties playing right handed guitars (out of misguided necessity) and truthfully I observe them and jam with them etc... and they are still a bit lacking in the groove. Enough that I wonder why they just didn't flip the instrument over and work from a much more comfortable perspective during those formative years of learning.