Why is "singing along" a relevant metric?

In Dublin's best music venues, nobody is singing along because it's brand new material from brand new artists. If you're singing along to well known songs in Temple Bar then I'm afraid you're missing some of the best music the city has to offer, in venues like Whelan's, Workmans, Sin É, The Grand Social etc.

Because in America we do not appreciate local musicians as i experienced in Dublin nor do we sing alongs in majority of our bars (maybe there are a few but none ive been to throughout the US & its not apart of our culture). We are a more subdued culture in this regards and as I believe worship/appreciate celebrity musicians over local musicians.