People mixing up all sorts of things - with the best of intentions no doubt but there are quite a few inaccuracies in what's been stated.
Tony's message that appears to have been deleted, sadly, as it shows precisely why you shouldn't post without confirming what you're saying first.
I don't need to go and learn more about plumbing than my plumber, more about wiring than my electrician. I trust them to do their job and get on with my own.
I'm more than happy to do the same with doctors.