The problem is a lack of funding, which leads to excessive competition and ties continued employment to sustained contributions.

Many results are obvious in retrospect, and such results are often the best ones. The difficult part with such results is framing the problem in the right way and asking the right questions. If you manage to do that, the result simply follows. You may still need funding and hard work to confirm your finding, in which case someone with more resources can claim your result, if they are aware of the idea.

I think the GP was suggesting that their reluctance was more about someone taking their idea. I still think it might suggest a problem with academia, but the summary would be closer to

"I don't want to live in a world where someone else follows through with my ideas without giving me credit"

It's still a problem because a lot of academics aren't especially well equipped to follow through with their ideas, which can create information silos that lead to ideas never being implemented. Still, I don't know if this is the biggest fish to fry: you have other silos like IP law and NDAs etc.

Academics have to eat and they're judged on the quality of the research they produce.

They're more likely to share their research then big tech once it's ready and they can get the credit they deserve.

This can then be used to succeed in future grants or if your institution is particularly strict, meet your publish quota to keep your position.

This feels like an unwarranted strawman. There are plenty of reasons for researchers to share openly at times and plenty of times it makes sense to wait until the meal is ready to serve before publishing.

grants are competitive

I think the sentiment is misplaced here (there is a legitimate concern for IP protection), but this is my absolute favorite line from Silicon Valley - small correction though: “… makes the world a better place better than we do”