Just like any other deep area of CS (databases, compilers, kernels, crypto, …) most people use a higher level system, abstraction, or library. You can build a d

Just like any other deep area of CS (databases, compilers, kernels, crypto, …) most people use a higher level system, abstraction, or library. You can build a distributed system on top of one of these things, but that doesn’t qualify you to implement (well) the core primitives. And I’d add, that compared to 10 years ago, a lot more people know the core stuff too.