You're using a somewhat non-standard definition of "purity", which makes your claims more confusing than they need to be. Haskell is usually referred to as pure, and has had encapsulated effects from the start. Your claims are true using your definition of "purity", but false using the more common one.
As a point of historical note, Haskell has not had encapsulated effects from the start. Monadic IO was introduced in version 1.3, roughly 6 years after version 1.0.
