[CiPHPerCoder]

NaCl/libsodium solve a low-level problem that even very few talented engineers with years of software security experience can be expected to get right on their own.

Using these features should still be done under the guidance of someone who knows what they're doing. There's a larger number of developers who can use libsodium than there are developers who could replace it on their own.

In a sense, NaCl/libsodium can be viewed as a "replacement for expertise" that is so rare it's nigh-nonexistent. (To wit: these libraries were created by multiple authors.) Rather, it places the capability to build solid application-layer crypto into the hands of mere mortals.

That doesn't obviate the need for good mortals. :)

[nickpsecurity]

Great explanation. That's exactly what it achieves.