That level is still somewhat prohibitive for a lot of folks. Schooling alone can cost quite a bit, and without this a lot of places won't take you seriously regardless of your self-study. This aspect alone makes the person unable to reach Pasteur or Curie's "mom and pop research" level.

Not to mention supplies. I worked as a lab assistant for a dude studying the effects of zebra mussels in closed freshwater lake systems in Indiana (dams and whatnot, where the mussel would need to have been introduced to the lake). Microscopes capable of counting the young, ventilation hoods (for preservation chemicals), scales, and methods of disposing of biowaste from the traps for adults? Yeah, that's even more - and this dude had a pretty low budget. What he did have was the time to put into the research which is yet another thing that alludes folks. Some fields of study really needs better equipment than we were using - plus it has been 20 years since then.

It isn't that the low-budget stuff or the "mom and pop research" is less valid or not good enough. It is that even that level is cost-prohibitive.

That was then, now is now. There are few low-hanging fruits left these days. Especially in a field where showing any effect practically requires a sample size of dozens to hundreds and an observation period of years to decades.