Nowadays we'd call that "engineer's disease". I wonder how many potential Von Neumanns were discouraged from branching out into other fields by jealous gatekeepers who assume that any interest in their field by "outsiders", especially technical people, is "epistemic trespassing".

I have yet to meet a (academic) researcher that doesn't like to talk about their research topic if somebody comes and is genuinely interested. I mean most work on a topic that has maybe another 10-100 people in the world who are interested.

The problem is that instead most people to come to them are either obvious crackpots, who think they have solved cancer (energy...) and contact the person because they are a biologist, physicist ... (on a completely unrelated topic usually). Or they come from a place of arrogance, i.e. "we do ... like this, our method is clearly superior you should adopt it", or even worse here buy our clearly superior method.

For every von Neumann you probably have thousands if not millions of crack pots with ideas not worth wasting time on. So I understand the scepticism

Seems to me it's less about gatekeepers and more whether what you bring to the table is useful to people in that field.

If somebody truly believes they have a useful model then they don't discouraged by academic gatekeeping, they go and build Time Cube.

Usually that's because the engineer is not a very good engineer, at least outside their specialty. If they had studied engineering more, they would have probably learned that other engineers are already doing the thing they proposed.

"Using methodology from a field known for its focus on methodology in another field" was still a novel idea in von Neumann's time. But because von Neumann and others did it, and because millions of people entered science after them, most combinations like that have already been tried. Breakthroughs from combining ideas from unrelated fields require something little less obvious these days.

If someone is equal in talent to Von Neumann it's probably extremely difficult to discourage them enough via gatekeeping to stop them from making progress.

It's highly unlikely, I think, that another Von Neumann was prevented. He was a singular genius.

However, the gatekeeping you mention definitely occurs to mere mortals who might have an interesting bend on existing ideas.