In a thread on what not to sing in UK Folkclubs the original question got somewhat lost in a plethora of other discussions. This thread might be more appropriate for one particular debate therein.
I suspect that the singing of little songs have made significant differences on the planet.   They have raised conciousness, on any number of issues.
I, personally, am convinced that the teaching of Irish Patriotic songs
( They're only Rebel Songs to the English , Unionists and uninformed) to schoolchildren in the Republic of Ireland prior to the 1966 celebration of The Rising, helped to raise a political awareness that some took into battle shortly afterwards. the Brown stuff hit the fan in the Occupied Six Counties 2 years after the 66 celebrations and the Irish National broadcaster stopped playing all the stuff that had been , on some ocasions beaten into us . They knew then and they were not known for their enlightenment, the power of song in effecting political change.