The idea is that instead of having to learn tens of different syntactic constructs with subtle and often arbitrary differences, you just have parentheses and use them to build everything.

This is such a undervalued benefit, once you've learned s-expressions, you can basically learn a bunch of languages without having to learn completely new syntax. It'll be slightly different, with different idioms and names, but a hell of a lot easier than doing the same across every "It's like C but 50% of the syntax is different actually" language out there, which is most of them.