i see your point, but when you get so-called competent sparks asking stupid questions like whether they can use 6mm to carry a current of 60A when a quick look in the regs or on site guide will tell them the answer, or why is the RCD tripping when OP has done no testing, this tends to get peoples' backs up. the other side of the coin is a DIYer hurling abuse when told the job is beyond his skill level.
I totally agree with your cable point. I've seen a few of these type of questions on here and it does amaze me that such a basic question has to be asked.
I knew approximately how to calculate cable sizing before I'd ever seen the regs.
I'd also agree with the DIY statement to a certain extent, but not all DIYer's are as stupid as some people would have you believe !
At the moment I would consider myself a competent/advanced DIYer even though I hate the ten DIYer, but that's what I am I guess until I can prove otherwise.
I certainly know what I'm capable of, what's notifiable or not, and I certainly know my limits and take no chances where safety is concerned, but I guess some people are not intelligent or knowledgable enough to know their personal limits.
I know a lot of you experienced sparkies believe that there should be some kind of national register for approved electricians and I agree that would be good.
As the regulations stand at the moment they can be interpreted in many ways which can cause problems for the DIYer and professional alike.
I can think of few situations where some clarification would be nice in a black-or-white, yes-or-no way but this doesn't see to always be possible.
It would certainly clear things up if everyone knew exactly how they stand.