In the vast majority of cases I'd say avoid it like the plague in any genre, but especially in the accompaniment of Irish music. There are exceptions of course. EG.,

The Southern Appalachians has spawned some good trad piano players. Uncle John Patterson of Carrolton, Georgia, is one who I particularly like.

Accompanists of Cape Breton fiddle usually bring a zest and a verve to the music which piano players in other fields would do well to note.

Elizabeth Stewart of Fetterangus, Aberdeenshire is one woman who can do no wrong for me, especially when she starts tickling the ivories in one of those medleys of Scottish dance tunes.