There's a simple distinction to be made between a session and a folk club. The session is an informal - possibly impromptu - gathering, normally in a public room, of people playing 'for the craic'. Other people have gone there to drink and socialise, often not knowing that there would be such a session in progress. In these circumstances, I don't think most of the musicians would expect silence. If they do, they can always find a quieter venue, or a quieter night. A folk club is normally in a private room. People pay to get in, and it is reasonable to expect that they have gone there to listen to the music. The person singing has, presumably, spent a certain amount of their time learning and arranging their material, and practicing it to an acceptable standard to present to a paying audience. The standard will, of course, vary; one would expect a professional to have done a lot more 'homework' than the amateur floor singer. But, whatever the status of the performer, people should respect their efforts, and one would expect musicians, in particular, to do so. Talking over the music is arrogant, and disrespectful, not only to the singer/musician, but to the whole audience.
And I don't know who Snail was referring to in his last post, but I, for one, am not blaming any particular generation. My earlier contention was that there has been a general decline in standards of behaviour in (English) society.
John Kelly.