Here’s an article on PetaPixel that compares a state of the art 36 Megapixel Nikon D800 (considered one of the best DSLRs ever made) with a 10 year-old 14 Megapixel APS-C Nikon D3100. The bottom line is that for web-sized images and small prints, there is really no significant difference.
This supports my case that 16-24 Megapixels is more than enough for most of us. It also supports the theory that you need to quadruple the resolution to achieve a significant improvement in perceived image quality. So in this case, all else being equal, you would need to go over 50 Megapixels to see a clear difference, except at very large print size of course.