The pointy shoes are a shibboleth. They identify a group not despite their impracticality but because of it. Another example is the belief in miracles, the more unlikely the better, because it is the absurdity of the belief that distinguishes you from unbelievers. There are oodles of such shibboleths in modern times, particularly in politics. Just think of any political proposition that is absurd on its face and more…
This isn't part of the definition of a shibboleth, as I understand it. A shibboleth is simply a marker of group identity (the original case was the speaker's accent when pronouncing the word 'shibboleth').
You seem to be referring to something more analogous to peacock feathers, where hewing to some practice in spite of its impracticality signals the depth of one's commitment.