I think it's part of them acknowledging that knowing about computers in this age is very important, and feel that they should learn more about them, but are reluctant due to time constraints / feeling then can't understand the maths / etc.. so they find excuses why it is uncool.
Technologists aren't free from this "fallacy" either. For example, when they hate on marketing ("I don't want to learn about marketing as it's all bullshit"), or when people from one technical field hate on another ("back end? man, that's just engineering, it's all about UI these days...").
In the case of hate on computers, it's usually combined with some component of nostalgia; What do we need computers (and computer people) for? Weren't we better off in slower times, without all the flashy stuff?