Use readonly wherever possible?

[D630]

Recently, I had to review one of my team members shell code. She is a 
Java developer, and used to declare variables with the final keyword. So 
in shell she was constanly using the readonly attribute like:

foo() {
        local -r bar=$1
        local -r lich=$2
        echo "$((bar * lich))"
}

I think that's unusual code in the shell-code universum. My first reflex 
was to say "No, don't do that", but I hesitate with my answer, because I 
have no idea what happens exactly in bash when a variable is declared 
readonly. So is there any advantage in using readonly wherever possible?