So far it seems like most studies are done by scientists / academics in a very closed off kind of way, but the true nature of science is open to everyone and with the right platform we might be able to use normal people to gather enough data to confirm or deny our hypotheses in a way that's much more open than the standard study.
Essentially, anyone would be able to test their hypotheses and either help advance scientific knowledge or at least provide extremely interesting markers that could be used as a basis to get funding for more rigorous / controlled studies. This approach obviously won't work well for every kind of question but just as the OP has highlighted: it's particularly well-suited for making self-experimentation more rigorous and I imagine it would work well for the social sciences.
Imagine if we gave independent researchers like Gwern the tools they needed to help answer more questions. If it was designed right: it would also be an incredible learning tool for the scientific method (since you could participate in the experiments + propose new ones.)
Are there any platforms like this in existence, I wonder? U-Uber for science?