How can dash be used as a main action if actions and bonus actions aren’t interchangeable?


I’ve found two twitter chains that I can’t seem to make sense of.

From Jeremy Crawford:

"Actions and bonus actions aren’t interchangeable." [source]

Also from Jeremy Crawford:

"Double dash in one turn can happen with dash as bonus action." [source]

So how can a rogue use both their action and bonus action to dash twice with [Cunning Action]? It is specified in [Cunning Action] that the [Dash] can only be used with a bonus action.