With that argument you could discard JavaScript because V8 is hard to understand.

C++ giving you the ability to create your own containers that equal the standard library is a bonus, it doesn't make those containers harder to use.

That's a false comparison. There's a huge difference between a standard container library, and the combination of a (a) best-in-class byte code interpreter with a (b) caching, optimizing JIT, supported by (c) a best-in-class garbage collector.

I would argue that it's reasonable to say that creating a robust data structure library at the level of the STL shouldn't be that arcane.