OK-
If folk music is about communication with the folk in the general sense, and I believe it is, there is only one instrument which can hold its own in a noisy crowd, which is the norm these days.

It can 'cut through' such a gathering, given the right choice of material and some ability with the instrument & maybe a singing voice?

Flutes and pipes and fiddles etc can be amazing on the concert stage or other formal setting for short periods but it's hard to accompany your singing with them! in a lively crowd, for me, to communicate with the 'folk' as I define them, the 'best' instrument
is the melodeon.
Mind you, I could be biased?