Many of the community/rock or if you prefer 'amateur' choirs near me are formed for people who have had difficulties in their lives, ranging from DV, serious illness, bereavement, trauma. Many people join because their confidence has hit an all time low.
These fun group activities are a way of getting out, making friends, chatting with people who have shared experiences and starting to feel good about yourself again. There is a joy that comes from performing (whether you are any good or not) that can be enormously restorative in terms of mental health.
I think to say 'actually you are shit, why don;t you keep quiet, or enjoy yourselves where no-one else can hear you' is pretty unpleasant directed at people, some of whom will have had a lifetime of being told they are shit, not good enough, they should shut up and know their place.
No one has to listen to any choir, - I've never heard of anyone being forcibly shut in a room and forced to listen to an amateur choir. Personally I get pleasure out of seeing people enjoy themselves, whether their singing is perfect or not. Good on them.
I don;t sing in a rock choir (although I have sung in a charity choir where we raised money for more reclining chair in our local chemo unit so more patients could be treated at any one time - we weren't great singers but people seemed happy to listen and donate)
But I have friends who have been through trauma and have joined rock choirs and the change is amazing -they have come out of themselves made friends regained confidence and joy in life, in some cases the choir has literally been a life saver. A haven where no one judges you, no one tests you to see if you are 'good enough', you are accepted for yourself and you have a good time.
Just walk past in the street if you don't like listen to rock choirs.