Agreed. Plus, I tend to see the autoharp as a solo instrument, not really suited for backup for the reasons you mention; it’s awfully ethereal. On the topic of playing melody on them, here’s Blarney Pilgrim and Humors of Ennistymon:
https://www.youtube.com/watch?v=nbKApkQe2Jk
So it can be done, and impressively. However, any other instrument playing the same melody would drown it out because it’s plain to see that even done well, an autoharp’s melodic capabilities are more in passing and not very strong. So it’s either solo, or we’re back to just chords. As backup, I could see it as a one-off for the craic, but not as an ongoing presence; I confess I’d get pretty tired of it.
I didn’t know that could work. Amazing. But as you say, I don’t really see that fitting into any session like context, not if it’s going all the time anyway. And I wonder to what extend the fullness of the lower range depends on the plug in amplification. Brilliant for a short spot at a concert though.
Couldn’t help thinking of one occasion where we were playing during some Willie week during the eighties. A hammered dulcimer player set up, quite uninvited too but let’s not even go there. She was brilliant but after a not too long while that very loud tinkling sound cutting through everything drove everybody in the room bonkers. Time and place and all that. There’s one for everything, on other occasions however…