There's a much more obvious difference between now and 100 years ago: 100 years ago the education and financial support for scientific research was largely a closed shop for European-descended upper middle class men. There are certainly many geniuses obsessively researching into areas that stimulate their intellectual interest today that wouldn't have had the opportunity to do so back then.

I'm not sure being a scientist was that unfashionable 100 years ago anyway: research labs were a thing, academic work was arguably more prestigious than it is today, fortunes were being made from inventions especially in fields where there were low hanging fruit, competitions and societies and exhibitions to celebrate scientific achievement had come into existence and the idea of inventiveness was even tied up in popular contemporaneous notions of national and racial superiority. There might be more subfields and more research to build on nowadays, but the stereotype of scientists being underpaid eccentrics certainly hasn't gone away and nor has the fact a mathematics prodigy can make a lot more money working in financial services than academic research.

I'm also unconvinced scientific progress has slowed because today's geniuses are working on interpreting our genetic code, modelling solutions to climate change and solving scaling problems in computation rather than drawing taxonomy diagrams, inventing new types of consumer electronics and breaking the land speed record.