There are literally thousands of excellent English musicians (and let's not forget the Americans as well) who are playing brilliant Irish music and coming close to Irish traditional styles. Certainly the vast majority of musicians in this country couldn't tell the difference between them and Irish musicians brought up with the music. Okay so those brought up with it could tell, so what? Most sessions are open and free to allcomers. Any session that plays reels wall to wall endlessly is boring diddly diddly to all but the incestuous few at the centre and certainly doesn't make good listening after half an hour. Similarly an endless session of humpty dumpty. For god's sake bring variety back!
If I was running a session and one type of music started to dominate I would deliberately play something entirely different just to make the point, or (gasp!) even sing a song.