I agree that today's stouter rims with welded joints and machined side walls make building much easier than it used to be. But there's still a certain degree of knowledge and skill involved. I've watched newbies, phase the flanges wrong, strip nipples, struggle with dish, and find all sorts of pitfalls that those with experience avoid.

Like most things mechanical, it's easy if you know how, it's fairly easy to learn, and if you have decent mechanical instincts it's possible to learn as you go and do well the first time out. But for a newbie without good instincts or a decent teacher the odds are that there'll be some error and trial in the process.