It is a demonstration of being able to read and interpret the chart legend, which is provided to you on the test. And knowing whether a frequency can be used to talk to FSS might be important someday. Just because you can't imagine why, doesn't mean it's pedantic.
I don't think you understood me. Reading a chart legend is exactly the sort of really really basic thing the test is screening for.
My point was very deliberately NOT saying anything about talking to FSS or whether that is useful or not useful. My point is that the chart supplement and chart user guide explains this very basic information to you so it isn't worth much to test if someone memorized what the underline means - they can always look that up.
I think FSS is useful. Basically I am saying the test doesn't prove much and some people will always just cram cliffs notes for a test like that. The fact that a test exists at all and will get some people to actually read the AIM/etc means the test did its job. The test only needs to be scored because some people wouldn't bother to study, read any of the FAA manuals, etc if the test weren't scored or didn't exist.