thanks a lot for this interesting thread and all the great contributions. It shows that the same problems occure here in europe too. I love jamming since I grabbed a guitar some 30+ years ago. In the beginning I always felt covering note for note wasn't creative and I always wanted to find my own voice, so in the first years I sat daily for hours in my room and jammed to records on my own and was playing with friends trying to write original music. a bit later I tried the cover thing, learned something from it, too of course. but I always felt that the more I played covers, I lost my originality on my instrument with originals. so I didn't play covers for many years.
when I moved from the countryside to the city in the mid 90s I started to join open mics with the usual cover songs, subbed a lot of gigs on bass and guitar and played on open jamsessions a lot and was also hosting open jams for some years. the jam session scene was great from around 2005-2014 here in hamburg, but then it slowly started to fade, and now the number of great open jams is reduced to max. 1 a month.
I'm not talking about jazz sessions which mostly are realbook jams over here and I experienced them to be a bit snobby to non studied musicians, which even became worse since all the "music" schools popped up.
My experience is that for a great jam where you can experience magic and songs developing from scratch, it is not nessecary to have highly skilled musicians, but to have sensible players who listen to what is happening on stage.
feel and an open ear are the most important things for great music.
Unfortunately I'm afraid the "death of true jamming" is a reflection of a development happening in our society. the lack of empathy and lack of the wish to truly connect to others result in bigger egos and lack of self reflection. and since "artists" usually show the essence of the state of humanity we can see this problem occuring on jam sessions a bit earlier than most other people.
but, from time to time I see young people who still "have" it, and this always gives me a smile. there is hope.
