Sure, you need to have strong starting pitching going into a postseason. Ideally, you develop a guy like Framber Valdez to fill that lead role, as he did for the Astros. Also, you need a really deep and really effective bullpen to win a championship. And you need your top hitters to hit.
Fans love magic wand solutions. Spending $80 million on two starting pitchers would increase the chances of winning a World Championship by a few percentage points. Now, if both of those pitchers stay healthy, pitch to their level come playoff time (i.e., don't pull a Verlander) and get the proper offensive and defensive support, then that increases the chances by additional percentage points. Trouble is, other teams are doing the same things to upgrade -- and so teams that had great starting pitching on paper go home early.
This is not to say that teams should not try to build championship-caliber teams because it's futile endeavor, but there needs to be more awareness that buying a Max Scherzer guarantees nothing, as Scherzer himself proved again.