Note that I'm very new to exploration of the details of the HTTP spec, much
less its implementation.

I would assume that, like many protocol specifications that are designed to
meet a wide range of needs, there are areas of the HTTP specification which
are less used, or rarely implemented, compared to other areas of the
specification. I wonder if there is any understanding of what areas of the
HTTP specification are essentially "moot", or are expected to not be ever
used by real-world tools?

In particular, I wonder about "Transfer-Encoding". Is this something that
is really used? In addition, how relevant are "byte ranges", and even
worse, byte ranges on entities requested with transfer-encodings?