I am not sure you would consider me directly in that space, even though the vast and distributed nature of that "space" seems unlikely to produce someone that can be considered equal part high level broadly knowledgeable enough, technical enough to make a statement about the work, in addition to muck around here to provide an answer. I think your answer is lost in the crevices of the nebula of dissimilar characteristics.
That being said though, take or leave by following boiled down opinion on the matter that it is essentially just a form of greed that drives this ethos you highlight. It's both negative greed of people not wanting to discuss their secret sauce that does or could make them rich and wealthy, especially if and when it comes as the expense of others (regardless of whether it is only their sub-conscience that acknowledges it), not wanting to expose things like the spaghetti code that makes up the core of a multi-trillion dollar enterprise of maybe even the literal fraud being perpetrated to achieve riches, some self-delusion that obfuscation quals security that hopefully will prevent nefarious actors gaining insights.
The very nature of the financial industry, a store of value, worth, and a huge closet of misdeeds and fraud that is chocked full and bursting at the seams to reveal the putrid innards; makes it a massively sensitive matter and domain. The behaviors and actions or ethos of the financial industry is not at all dissimilar to when you interact with other dishonest and nefarious and secretive types who have dirty secrets to hide and ill gotten gains to obscure and squirrel away. But there is also a layer of honesty that must be maintained. The notion of "disrupting" the financial sector with the trademark wonton recklessness of the Silicon Valley mentality gives me shivers, because when, e.g., the WeWork fraud
One may as well have asked why African government officials don't publicly speak about how their government work or ask the CCP how China really works. But one could also even ask that question closer to home like how massively lossy Silicone Valley unicorns can exist or one may also ask for an audit of the DoD (which, interestingly, the recent attempt to audit the Marines led to the Auditor refusing to sign the audit) or the Federal Reserve (a set of private bankers that control the money supply without any accountability, oversight, let alone limits or balance of powers). Those are ALL equally sketchy and nefarious deceptive and manipulative smoke and mirrors slight of hand operations that one could ask the same question of why does not one speak publicly about their work.
You may be one of those that realizes that there is a thread that runs between all of the above.