I feel like there's an opportunity for a web platform for the collaboration of (independent) researchers. Some place where I could propose an idea and others could tell me why that idea doesn't work or if it's already been done. And if the idea doesn't have any flaws and hasn't already been explored, then other researchers could help me perform the research or "fork" the project to go down different paths.

I think some platforms come close. There are places to ask questions (e.g. StackExchange) but they don't seem to like "what if" questions and if the idea is good there's no good way to follow up over months or years. Github works for some fields where the idea is tightly coupled with the implementation (e.g. some computer systems fields) but not for others.

I guess I would just like a place to discuss ideas. In academia it's common to discuss nascent ideas within your lab, but larger collaboration happens at things like conferences where you're presenting only the ideas that worked out. I think such a platform could make independent research like you're describing much more effective and attractive.