Comment by ian_holt

>In my experience, a decent proportion of people have always been nervous about joining in. I'd wager that for many of the onlookers it isn't driven by a creativity/participation thing, it's just a (pretty normal) fear of embarrassing themselves. Scroll back 30 years and I would undoubtedly be one of those awkward teenagers wanting to join in but scared to do so out of fear of embarrassing myself.

You just described me 40 odd years ago :))