Yes, of course they do - that was my point. What skill level is required depends on what "assembly" really means. Despite the claims of Code41 for ultimate transparency, they provide little actual information.
I would assume (since that's all I can do) that this would include as a minimum:
1 - gathering of components
2 - cleaning of the case interior
3 - mounting of the dial
4 - mounting of the hands
5 - installation of whatever gaskets are involved in the case
6 - trimming the winding stem and mounting of the crown
7 - final timing checks as a minimum
8 - verification that functions work
9 - pressure testing
10 - mounting of whatever strap or bracelet goes with the watch
I would also assume this would include any adjusting or troubleshooting required at this stage, so regulation as needed, troubleshooting of failed pressure tests, etc. As I said, having gone through pricing this out myself, and quoting more than one vendor, there's no way I'd be doing it for $43.