>That doing you are referring to, how is it related to advancing the state of the art?
It's related in the following way: if you are advancing the state of the art, you are really doing mathematics. The converse is not true, there are many ways to do math without advancing the state of the art.
>So in theory, at any point in time you could remove the books with the spoilers, lock up the classroom and let the students rediscover on their own. That might confer the excitement, but it would be glacial.
Essentially, yes! What you described is called Inquiry-Based Learning [1][2], and is a very well established (and woefully underutilized) educational practice.
You are correct that on the surface, it appears that IBL is slow. However, I would argue that students learn more in the same timespan.
Why? Simply put, you don't measure a house by the number of bricks. A shed you build on your own is a house, but a pile of bricks accumulated over 10 years is not.
Perhaps a student who understands the Fundamental Theorem of Calculus and the notion of limits has learned more Calculus than the one who has learned 100 ad-hoc symbolic integration techniques. It's a travesty that today's education emphasizes the latter.
>So you add a teacher, to nudge the students into the direction of the fastest path. That quickly turns into full-on spoilers...
...and it really doesn't have to be this way.
>Is there any place in the world that teaches math in a different way?
Yes, the US. In some places. Personally, my spouse designed and taught an IBL university-level math course; it's something that exists and is (very slowly) spreading.
>That being said, the author was studying applied mathematics. It's kind of their job to not get excited and instead ask the boring question of "how will I ever use this in real life".
True, but the applied mathematicians I've seen still have a lot of fun with it. That's my complaint - that the author didn't get to enjoy the kind of math he was doing. I don't think that it's because his math was applied.
[1] https://en.wikipedia.org/wiki/Inquiry-based_learning
[2] https://www.edutopia.org/blog/what-heck-inquiry-based-learni...