I guess it's cheaper to try and extend this whole facebook/cambridge analytica story than to do actual journalism. What's more you get to attack a business rival (doubly true for wsj v google).
If the cambridge analytica story was about selling cars or home appliance, it would have been forgotten in a few days.
Edit: And perhaps it's a good thing that it was about the elections? It would mean that it might force a change on first Facebook, then maybe other internet companies