What do you mean harmless?

It means that although it has an impact, it has no harm to the main aspects.

This means that when people speak or do things, although they unintentionally hurt the interests of others, although it is correct, it is not the fundamental interests of others, but only the skin of their interests, and will not cause serious consequences.

The source is Wu's "The Present Situation of Seeing Strange Things in Twenty Years", which is the 25th time. The original text says, it doesn't hurt to be such a stubborn person without asking him if he is true or not.