This is why Ilya Grigorik's book, High Performance Browser Networking, exists. It's a great reference to that end as well.
But then you need to understand the differences between HTTP 1.1 and 2.0 and how it handles multiple requests from the same page. 1.1, you would probably be better off with a single concatenated file, 2.0, perhaps several. And then what about compression? Any good UI developer should be considering compression of that file, cache control, etc.
I see too many front end developers shy away from this stuff and create bloated monstrosities. They feel it's someone else's job... but if not the UI developer, then who??
This stuff does get pretty complicated. Mainly because the tech is evolving fast (browsers do a lot of tricks now). Even in HTTP 1.1, there are times where multiple files might be more interesting due to how large files are handled
Well, indeed, the higher level protocols, like HTTP, DNS, etc, are more useful on a daily basis.
I've work with many of them, very good about Adobe products and Apple last thing, but clueless about, why their final code is of poor quality.
Fortunately, many of them did get their Ego down, when the web did start to move from markup (html+css) to code (js). Until then, they did take any feedback from a sysadmin, as an attack to their work.
About developers and architects... they should simply be the final support (24/7 calls included) for their work and changes.
As a side note... a sysadmin IS A developer (a systems developer). An application developer, usually should be a systems developer if he/she is working in a project that includes a platform to run (unless he/she is just uploading an app to any appstore). An operator with limited privileges, is just that. The concept of "pure developer" or "pure sysadmin" is so 199x...