Certainly. However, there's a difference between keeping scalability in mind, and actually implementing/maintaining a complex database scaling system at the onset of a project.

Edit: I would also add that most projects I've seen tend to undergo one or more large refactors / redesigns before growing to a size where complex DB scaling is needed. This is, of course, speaking from the perspective of a small startup or pet project. If you're writing a new feature for an existing product where you can assume that it'll have lots of users, then you would obviously build scaling right from the start.