Reason #2 Security
Do you know how to provide the highest level of security to all the different parts of your business within the Meta universe? With so much at stake from personal data, to credit card information, to the time, effort and energy it took to grow your audience - this should be a top priority for all businesses.
At the very basic level, you’ve hopefully enabled 2-factor-authentication already in your Facebook & Instagram accounts. But that just applies to you. What if you need others inside your business to take on certain roles? Or you need to allow access to external providers such as Virtual Assistants or Ad Managers? Without a Business Manager, you can assign *some* roles through your page admin settings or you would need to share private log-in details, giving them open access to your personal account and enabling them to act in your business as if they were you (which is a huge risk whether you gave them your actual log-in details or used a service such as LastPass).
Then if either you (or someone acting as you) were to get ousted off the platform for a violation or because you got hacked or because someone you trusted did something bad or made a mistake, that’d be game over with a hard and sometimes impossible route back. By ringfencing each area of your business inside a bespoke Business Manager, you are protecting every other area of your business from each other and therefore mitigating risk. Think of everything you’d lose if one domino were to fall. I don’t want that to happen to you.
Having a Business Manager in place allows you to set up 2-factor-authentication for all users, with everyone accessing through their own profiles, either as an admin, an employee or as a partner - you decide. You get to keep billing information and other sensitive data separate and secure from other users in your business, along with permissions over who can do what. If protecting your business from security issues is of concern to you, then having a robustly set up Business Manager is the best way to do that.