"'the Irish setup where everybody takes O'Neill as the bible and nothing ever gets formally added to it. '
Now there speaks someone with no knowledge whatsoever about the current traditional music scene in Ireland.
There are any amount of tune collections in Ireland these days, the difference is that Irish musicians learn the tunes at home, and don't take them to the session.
"For the most part Irish music buffs will say they learned a tune (if it's not in O'Neill) orally ..."   Ireland doesn't have "music buffs", they have musicians who play traditional music, thousands of them. "O'Neills 1001" is actually fairly irrelevant as a reference book these days, the settings within certainly so.
Anyway - the title of this thread is : "The current state of folk music in UK" - nothing whatsoever to do with Ireland. The OP was asking about the UK.