Specialisation came to the fore during the Industrial Revolution and achieved a form of preeminence in the 20th Century that hadn’t existed elsewhere in human history when knowing, at depth, a wide variety of skills and disciplines was either essential for survival or in order to be considered a well-rounded individual.
The internet, not without ongoing battles against vested interests, has solved the discoverability challenge faced with approaching the wealth of knowledge created in the past few centuries. For many of us aspiring polymaths (and I agree with the other comments here that a polymath isn’t someone who knows “everything about everything“, but rather knows “a lot about a lot” or “enough about enough”) the challenge is mental and societal.
We convince ourselves that we must specialize to succeed; most schools and many workplaces promote the same. Yet creativity and insight so often depends on interdisciplinary knowledge and the ability to use our brains to connect novel ideas.
It’s not the right choice for everyone. If you want to be the best in the world (or the top 1%) at something, then specialize. But most of us are more varied than that, which has benefits for us as business owners, or employees, and as humans.