And also, IMO it should also always be played with the right lilt and rhythm. If the guitar player is loudly playing a regimental rhythm to a tune with a lilt or a jig or reel etc, it is at cross purposes.

I should come clean, 'fess up, and say that I play Celtic harp at our session group. I'm self taught, I don't play the melody at the sessions, just the chords or arpeggios of chords, but I try to fit the rhythm of what I am playing to what I call the lilt of the tune. If a guitarist is playing a loud, fixed rhythm e.g. just one strum for each beat in the time signature, or one of the mandolin players in our session group tries to force the pace and make it into more of a rock music interpretation, it's very difficult to play the rhythm or accompaniment which belongs to the tune.