Dick, any deficiencies in the methodology of collectors are regrettable, but do not undermine the fundamental concept expressed in the term "folk song". Let me be clear that by this I mean "traditional" song, since the technical meaning of the term has long since been overwhelmed by the vernacular usage.

The fossil record, as unearthed by the collectors, shows that a certain body of songs and tunes have undergone a process of Darwinian evolution as they have circulated between singers and musicians. The term "folk song", or if you prefer "traditional song", is useful, but only in certain contexts, to describe this body of music. There are of course other contexts where it may not useful.

I still don't understand your antipathy towards it. If you don't find it a useful distinction then by all means ignore it. But many of us do find it useful, to understand what gives a certain type of song certain characteristics.

You say that "no one can define a folk song". I am perfectly happy to use this as an objective test to define a "folk/traditional" song in these terms because for certain purposes I find it useful. I don't see any problem with doing so. However it is only one of a number of tests which could be applied to a song - personally, being a performer and consumer of music rather than an academic, I give priority to the test of whether or not I like it.