Because strategy A beats both B and A+B. It's either VHS or Betamax, not both. And this again has to do with worse-is-better. A+B could be wise in certain scena

Because strategy A beats both B and A+B. It's either VHS or Betamax, not both. And this again has to do with worse-is-better. A+B could be wise in certain scenarios, but it's unrealistic as it requires double effort in all fronts, generates market uncertainty due to doubious messaging and no immediate gains in time or costs.