Now, this is not uncommon each software has its own advantages and disadvantages, and therefore they each use one another’s strongest features.
So if magento.com is using drupal for its website then possibly it is doing the best, because magento is known to be the best ecommerce software BUT not a content management system. So if the owner is implementing it then who are we to differ.
I don’t suggest magento to a customer who has 8-10 products and is not that keen on its ecommerce features, anything from woocommerce, prestashop, to zencart can do the trick, why to sell magento to a customer who has a very simple requirement.
At englightened our magento experts study the requirement and only then suggest the best possible solution.