"I'd be hard pressed to find a reason not to go this route at least once in your life. I know the material pretty well but I still re-read Stevens books every few years just because it is so good."

Then again, that's a lot of effort to spend on something that the vast majority of us don't need to know in much detail. The main reasons for knowing all the details are

- to write a new networking stack, or working on an existing one;

- to write or maintain server software or routers or caches or other software directly involved in networking;

- to break or exploit existing software.

(obviously 'because it's interesting' is a valid, but not practical reason to know)