The assembly is the easy part though. You could do it at your kitchen table if Apple sold you a kit with the parts Ikea-style. Don't read too much into it. Making parts like the CPU or screen or what is much harder.

The fixation on assembly is a leftover from a time when things were made from much simpler parts like a pair of jeans made from fabric and buttons. In that case the assembly is a bigger portion of the actual work and bigger portion of skills.