I guess I might be too accustomed to the idea of growth through confrontation, and it's not the first time I have noticed it being a liability. I guess part of the reasons for that are the way I have been educated (that is : strong parental criticism used to make me react in a better direction).
You've got a point.
But I don't believe that argument is a defence mechanism. It can bring great enlightenments and conclusions.
Also, not everyone is ready to actively listen to any kind of self-expression. There is often a threshold of quality to be crossed for most people to listen to what one has to say.
Does self-expression that no one wants to listen to enable us to grow as persons?
And besides that, even if self-expression was always benefiting to the person that expresses themselves, sometimes it can be very unenjoyable to the rest of the people, if not downright hurtful. Self-expression without taking into account the possible impact of what is expressed is not something that I would approve of.