That's the nature of science, no one person ever discovers a drug independently. All new science is build on the basis of old science.
If you wanted to sequence a piece of DNA in the 1980s (an entire genome was laughably out of the question), you would use Sanger's method and get a few hundred base pairs in a month. Maybe an entire gene in 3 months. Now we can sequence whole bacterial genomes or genotype a million SNPs in an afternoon, but gaining new, important knowledge is still much more expensive.
As a general rule.... but it's not like we know it's impossible these days. Who's to say that a lone researcher won't come up with a startling simplification of physics? Maybe this won't ever happen. The point is we don't know, and it's not as certain as what your comment implies.
Peace.
You could have said the same thing in 1900, eight years before the publication of the first paper on general relativity, arguably the most important advance in physics, ever, and something Einstein did independently.
Tthe Einsteins and Maxwells of the world don't come along very often, and the fact that we haven't had one in awhile is more a reflection on that rarity than any characteristic of modern science.