There’s a wonderful little carpentry museum in Kobe, highly recommended:

https://www.dougukan.jp/exhibition?lang=en

It focuses a lot on the evolution of precise woodworking tools, like saws and planes. They also had examples of complex joints, made without nails or glue.

There are a couple of Japanese joinery books out there. One that I've read gives the reasoning for all of the joints in the Japanese tradition for joining two boards end to end (thereby creating a longer board, in effect) is that the timber available for building in Japan doesn't come in long, straight lengths.

I can't tell you if that's true or not, but I have a hard time seeing folks putting so much work into developing such joints without a pressing need for them.