Mogensen said
"Scripting wins by making the environment smarter, at the expense of predictability."
That thing with lack of predictability doesn’t fly, at least not with your example which rather displays a lack of Perl knowledge 
The first example does not result in string concatenation (should have used the “x” operator, not the “*” operator for that), but a numeric operation (so $b contains 0). That’s basic to how the Perl type system works. So in this case it’s predictable if you know the language