I agree that no one could get all the information from devs. Even we are getting all the information from devs (just assume for an instance), what we could do about future failures of that project? Still we need to bear the risks which is somehow very much equivalent to those hidden things before investing.
Practically it will not be possible to gather all the information of one project and verifying them before finalizing the decision of investments.
Your statements are making sense. When we could not do anything about the future happening like unexpected debits or failure of concepts, I agree we cannot do anything if devs hide something from investors.
At the same time I guess if we have some checklist to do due diligence and if we are not getting enough information to complete that checklist then we can skip investing with that project. Usually people are going through white paper, roadmap and then team members and if they are finding those things satisfactory then they may go for investing. Other than this list, I guess there will be no other area is available right now for verifying one project before investing.