That's odd. It loads up just fine for me with no paywall.
Check this out for more: https://allusesof.com/math/51-amazing-uses-of-calculus-in-re...
The point is that calculus is used to solve all sorts of problems. Sure, you can say "...not in my experience" but that's one experience and not representative. You just happen to a) not work in a realm where Calculus is used and/or b) work within that realm only on problems without Calculus.
That is why I questioned whether knowing calculus is really a piece of fundamental knowledge that allows a 10x performance increase. For the majority of people it's not going to help them. Even if they deal with calculus in their field, I don't see it providing a 10x increase because unless one is mathematician, the calculus portion of their job will be inconsequential and likely be automated or computed for them.
OK no argument there. The OP statement was "For example ... Calculus for solving all sorts of problems" so it appeared you were taking issue with the idea that Calculus can be used to solve all sorts of problems. Your argument is clearer now: even if Calculus can be used to solve all sorts of problems that doesn't mean that it is "fundamental knowledge" for most people.