The perception of what a polymath is is changing incredibly fast, as both the floor and ceiling for being passable or outstanding in any field is rising exponentially. For the last 50-oddish years, it's been the case that being proficient with a single piece of software can make you an invaluable asset in industry; understanding the concepts behind the software and the problems it solves even moreso. Rather recently, we've reached a point where software ergonomics, freely available education and information, and even AI assistance in development or usage have lowered this floor in terms of cost, knowledge, effort, and skill. For example, it's trivially easier today to create a 3d animation than it was 5, 10, or 20 years ago, and the visual quality of it would be similarly disproportionately better.
The domains of different crafts are ever-expanding, including all of their history and all new developments, of which new developments seem to be coming at an ever-increasing pace as populations grow, internet access grows, and the free time of populations spent doing things other than merely surviving grows. There is a larger and broader base of knowledge necessary for a person to be considered competent in the current state of anything, and the number of disciplines is also increasing. Two decades ago, having a person specializing in frontend development for a specific web browser would have been unthinkable.
All of this work is built upon the backs of other people. Game engines, 3d modeling and texturing and animating, language design and implementation, audio software and sound design, graphics libraries, runtime optimizations, operating system APIs, networking improvements, distribution networks, etc. etc.. To think that any one person could possibly create everything they use to then create these final products, no matter the scale they are, is ignorant.
> For example, it's trivially easier today to create a 3d animation than it was 5, 10, or 20 years ago, and the visual quality of it would be similarly disproportionately better.
True, but this also means that the bar has risen for animations in general, so while you might be able to create animations today as an amateur that is even better than the animations just five years ago, it still won't come close to what professionals can actually achieve today.
Your very last point speaks a lot to me though, almost every effort people are amazed by have at least two people involved, indirectly or directly, and attempting things like this on your own would be a fool's errand.