"Tradition" doesn't mean "how we used to do it but don't any more", it's "how we still do it", including things that we didn't use to do.

Much of our present way of doing it is a recent tradition, which is another way of saying a living tradition. Playing a range of instruments together is very much an example of this.
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I personally find a bunch of musicians playing together for their own enjoyment can make for a much more enjoyable social evening than a set of people trying to entertain me, even if I'm not one of them. I suspect there are quite a lot of people feel that way - the people making music over in the corner are a pleasant part of the environment, along with the others playing a darts game that I've no intention of joining in with. It's all part of what makes for a good pub.