Because if you assemble yourself, and it doesn't turn on, it's your job to debug which part is failing. If you buy pre-build you get a warranty for the whole th

Because if you assemble yourself, and it doesn't turn on, it's your job to debug which part is failing. If you buy pre-build you get a warranty for the whole thing. We had some people at work buy parts and it was fine for a while, then became a nightmare, unstable machines where we could never figure out what part was to blame. It isn't worth paying Dev's salaries to let them debug their faulty hardware.