I think there is a difference between a folk club and a folk pub. Members would know to keep quiet during the quiet songs.
However, remember the context in which many of these songs were originally sung. Flash girls, the swell mob, the press gang, soldiers, sailors, rakes and gallants ready to slit a nose at the slightest provocation -- all pouring back porter, gin and brandy and probably puffing on cheroots or pipes. If anything the modern pub is pretty subdued.
I have nothing against lively pubs. The music fits the context.