The link is because Microsoft's account system is such an old beast that a proper account switcher, like the one Google has, is completely out of the question.

The link is because Microsoft's account system is such an old beast that a proper account switcher, like the one Google has, is completely out of the question. Instead, it seems the product team for M365 / Office.com created this high-level account linking process to make it at least palpable to the majority of users that only have one enterprise-based account and one personal account. If you happen to have more than 1 account, the account switchers on anything other than office web apps is going to break.