You are right that it would be nice if people only spoke of things about which they were expert.
You are correct that it would be better if people spoke about what they know more about.
You are wrong in saying that people should comment on topics they understand.
A boy wearing red is sitting on a bench reading.
The national economy was doing great.
I think she will marry you because you are old and ugly.
Three men are standing by water.
It was the exact same man who stood before them.
It supposedly will bring more money into the system because returns in the private sector are higher than government bonds.