I think they perceive it as a threat to their...skill? If everyone can casually swap out parts without any effort nor risk, it invalidates the experience of the people who had the will and ability to perform the work. Also, it might be a case of "it was always done like this." Many computer nerds from the 90's are now approaching or beyond their forties. Getting old sucks, since the things from childhood tend to fade away, replaced by something new and alien.

That is my guess. Short of obtaining the disturbing ability to read minds through the internet, I have to make assumptions.