absolutely correct,stylistic convention,is exactly what defines it,but it is not the only component.
but the folk process also plays a part sometimes,but just because something is processed it doesnt make it a folk song,because style of melody and lyrics are a consideration in determining what is a folk song as well.
we define JAZZ by style or a mixture of styles and by the fact the music is about improvisation.
international folk music includes many different scales and styles,but it all has something that tin pan alley does not,and it is not just aboutthe music being processed.
lily the pink, will never be a folk song even if a few of its words get altered,however Masters OF War ,is a folk song without one word of it needing to be altered OR PROCESSED.[itsabout style and content]
never mind what BobDylan says[he nmay be right me may not be a folk singer]but his song is a FOLK SONG.