So many weasel words in this 'complexity of products', 'good results', 'fair degree of skill', 'specialised tools' that I defy any random dozen people to agree as to what was meant. The whole concept is so wooly that I believe it could only have originated in the US product liability industry.
Maybe, maybe not. The problem is that the whole model railway business is a classic long tail. Many different products selling in penny numbers over many years.
None of the kits I've designed in the last few years require any soldering.