No doubt both solutions have merit, but Drupal requires an army of
developers in order to implement the solution. Remember, free
isn't always free and Acquia being a services organization knows
that all to well. I will say you are incorrect that Mid-market
companies average licensing cost is $450k. I would also argue that
implementations costs are FAR lower than what you describe for a
mid-market or public sector customers.
Keep in mind Adobe is the leader in the WCM market for a reason.
Adobe is developing a Marketing Cloud and employs an army of dedicated
developers to building a unified platform far beyond that of Drupal.
Open Source isn't free
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