>> You’d be astonished how correct is this.
No I know it first hand :)
I'm also not a cross-disciplinary expert, to be clear. When I say it's hard, it's because I find it hard! My strength is in discrete maths and logic. I can deal with continuous maths because I need to keep abreast with the latest statistical machine learning developments but I don't think I would ever be able to contribute directly to say neural networks research, unless I turned it into a logic-based approach (as has been done in the past). To be perfectly honest, if deep learning didn't happen to be the dominant approach to machine learning, which forces me to pay attention to it, I doubt I would have followed my own advice and looked far beyond my narrow band of expertise.
But, that's why we're supposed to have collaborations, right? I can pair up with an expert on neural nets and we can make something new together that's more than what we can each do on our own. In the process we can learn from each other. That stuff works, I've seen that, too, in practice. I'm working with some roboticists now and I've learned a hell lot about their discipline and hopefully they're learning something about mine. I am convinced that in order to make progress in AI we need broad and wide collaborations, and not just between symbolists and connectionists, but also between computer scientists and biologists, cognitive scientists, whoever has any idea about what we're trying to achieve. After all, a computer scientist can only tell you something about the "artificial" in "artificial intelligence". We study computation, not intelligence. If we're going to create artificial intelligence we need to collaborate with someone who understands what that is.
The hard part is to kick people out of their comfort zone and to convince them that the other experts are also, well, experts, and that they have useful knowledge and skills that can improve your own results. And seen from the other side of the coin, from my point of view, it's very difficult for me, as an early career researcher, to convince anyone that I have useful knowledge and skills and something to contribute. It takes time and you have to make your name somehow otherwise nobody will want to work with you. But that's how academia works.
It's just not a great mechanism to ensure knowledge is shared and reused, unfortunately.