What people need most is encouragement with a rational approach to a large project. With this information, first timers can grab hold of a tested method for implementing their project. The problem with being led by professional contractors is that they quickly forget their learning curve. After coming up through the ranks of construction teams, they really don't make as many mistakes as the amateur. The details of their learning process, once laid to paper, have been refined, with the potential pitfalls removed. They do not describe the possible failure outcomes of the procedures. I don't believe it's intentional, It's just humane nature. Skilled craftsman take for granted the skills they learned when completing a task that, to them, has become second-nature.