I can't find any country where they do this to their culture. Why is there a 'revival' and a 'tradition'? Anyone who attempts to pigeonhole on these two definitions is going to come to grief. Harry Cox, Sam Larner, Joseph Taylor, to name but three can all be shown to have used written sources and to have invented their own material. By the same argument, most singers have learned stuff from aural sources. Mary Taylor (Joseph's daughter) learned her father's songs but was roundly rejected by the 'revival' and those arbiters of what is 'real'. Similarly, her brother John was considered too 'churchy' and similarly rejected despite both fitting the 'traditional' criteria perfectly.
The term, 'revivalist' has been, and is, used perjoratively (not sure I spelled that right) and is unhelpful. Again, in my neck of the woods both carol singing and brass bands are 'traditional' music and involve copious use of written texts. I have learned loads of stuff from other singers but don't sing their stuff – because its theirs. Its all a mystery to me. Does being literate automatically render one 'not trad'? If that's the case then Walter Bulwer and Bertie Clarke both drop into second division by being classically trained at on stage. It's also interestig to try to get hold of that great Klezmer fiddler, Izaak Perleman. You'lll have to look in the 'classical' section in the record store because that's what that 'traditional' musician is most famous for.