You should also consider that during the worst of times for Catholic landowners, the period of the Penal Laws following the 1680's and 90's wars, O'Carolan and others were able to find Catholic families to support them. In other words, harpers declined at a time of stability, and in some cases incerasing prosperity, amongst Catholic landowners. Changes in fashion and taste amongst patrons lost the tradition, not opression. Leave that style of history to Facists, and Balkan politicians. This was organised by the Joy-McCracken families, and done by Bunting.
History is always too complex for simple explanations.