If i wished to sing Opera, I would have no problem with trying to use clear diction and doing breathing exercises so that i could hold a note without going flat.
Good singing technique can be ;learned and benefits performance in whatever music genre.IMO
As far as I am concerned having a good singing technique, helps my confidence in being able to give a satisfactory performance.
as regards traditional singers, there is no set rule, some just went down to the pub for fun, however singers who entered singing competitions example[ joseph taylor], had a different approach.
friends of mine who knew Harry Cox have told me that his attitude towards singing was differnt from Sam Larner, to be didactic or dogmatic about traditional singers attitudes to their songs is a mistake.