I believe the common value of being a generalist comes from the fact that you might be less prone to being biased or locked in a tunnel vision when evaluating a situation, since generalists would typically have a more complete world view under various angles and multiple lens. Specialists are often biased with their specialized knowledge and would only know how to apply it even when trying to solve problems outside of their expertise. As they said, when all you have is a hammer then everything you see becomes a nail.

The second law of thermodynamics indicates that our modern world will only become increasingly more chaos, which certainly seems to have been the case so far, therefore possessing the ability to assess the world with an unbiased mindset and under such clarity can be a huge advantage.

Though the most important value from being a generalist probably comes from getting around the diminishing returns effect. We are approaching a state where it’s becoming harder and harder to generate new knowledge in any particular single field, and yet the possibility and potential to combine existing knowledge between various different fields are rarely explored and still widely open.

Most people only specialize in a single track of expertise, they are either a doctor, a mechanic, or a fisherman, but they are rarely both. Those who possess knowledge of any two industries and are able to effectively combine them together will have the potential to generate a completely new piece of valuable information. This in turn will lead to more creative ideas and innovations. In a world where everything becomes increasingly saturated, this is probably the reason why being a polymath or a generalist is going to become much more desirable in the near future.