Some people - who do understand type systems - only think of static type systems as type systems. And in that regard they might look at "dynamically typed langauges" as having "weak type systems", since they are often just unityped (only have one type).
I agree to a degree, though some things are at least confined to a certain dimensions: like strong/weak typing. A continuum more than a binary distinction, but at least you can say things like "stronger" and "weaker" than something else.
(Note that I wrote "weak type system", not "weak typing". "Weak" here is a just a generic adjective, and not meant to be precise.)
