I'm all in favour of some workshops to support floor singers. I don't think it's a question of "formal teaching", more an opportunity to think about and discuss what you do and how to do it better, and compare ideas and techniques, preferably with input from one or more experienced and successful performers. I've attended this sort of event at festivals, weekend events etc, and have found them very useful.
It always surprises me that some people will take a lot of trouble to tune their instrument properly and take lessons to help them play it well, but give no similar attention to the way they sing.
Apart from vocal technique, there's the whole business of deciding what to sing and how to introduce it, finding a key, learning words, whether to go for chorus songs, use (or not) of accompaniment, etc. Not to mention coping with stage fright, sore throats and other difficult situations (first or last song of the evening; someone's just done the song you've been practising all week; how to follow a very confident and popular performer, etc.)
And, if you can bear it, getting up in front of the workshop group to sing to each other and accept constructive criticism can be really helpful. What is there to lose in considering and discussing these things together?