It used to be the case that folk tunes turned up in sessions and for dancing. Tunes were for ceilidhs and morris sides, and for groups of people all playing together. Musicians might throw a tune or two into a set dominated by songs. What was rare, was getting a folk gig, or a set at a festival that was all tunes. A friend of mine who was heavily involved in folk club and festival bookings considered just tunes to be a very hard sell to an audience.
In the last few months, I’ve been to two gigs that were purely folk tunes. Leveret, and Knight and Spiers. Both gigs were well attended by people who were clearly very happy to spend an evening listening to folk tunes. I enjoyed both immensely. I’m aware of other groups who do just tunes, in recent years there’s been more of that sort of thing.
Of course in classical music, people expect to listen to music with no singing. There’s nothing weird about it, but for whatever reason, folk audiences weren’t up for this, or were assumed not to be up for it. I’m not honestly sure what’s changed, but I think something has, and I think it’s rather exciting.