It's hard not to giggle when the conclusion right after "Smart constructors" says "Do these ideas belong only in functional programming? While they are practiced more there...".

Ah yes, because using constructors to ensure that new objects are in a valid state is virtually unheard of in object-oriented programming.

One thing this article does is assume extreme functional mindset, I dont even think OOP enters into the authors mind- With that context, I think that statement isn't about object constructors but type constructors.