I agree with you. There is a structural problem with the view put forward by the parent. If the validity of a view relies on I/O being the bottleneck, it encourages coding practices among that keep the implementation I/O bottlenecked. Once you already believe such a thing to be true you have little motivation to challenge or overcome it.

It is not the case that I/O bottlenecks can always be overcome, but it can often be, depending on circumstances, provided one tries of course.