Definitely true, but the way I think of it is that you should go with the default unless you have a reason not to. Things like fear and depression are useful tools but if they get out of control and only then are they mental illness, for example. In all of your examples, the person can know better, but when we're talking about the type of injuries from the OP then we usually don't unless we've consulted with medical professionals (or are one ourselves) so it makes sense to start with the default.