Many current problems are simply too complex to be solved by a single person, often because it requires expertise from very different fields. High energy physics, biology and neuroscience come to mind. There is not a single person who understands all aspects of CERN. Likewise there isn’t a single person who understands how to 1. Build a large scale Electron microscope to acquire high res images of an entire brain 2. Analyze hundreds of terabytes of data to make these images usable and 3. Analyze the results which would require highly specific domain knowledge of neural circuits or other biological features of the system you are looking at. My experience is opposite to yours. You are lost as a lone researcher in many fields and the best papers these days are written by enormous collaborations.