> It's a perfectly mainstream thing to build your own PC from parts.

Is it? Most PC (or notebook) users buy whichever one is on sale at the store, or they use one provided by their company. This does not strike me as inherently different to how people buy toasters or dishwashers.

Of course, there does exist a niche of people who like building their own PCs, but this does not imply that this is the mainstream case.