Current MBA student here.

I did online classes. Read books. Still signed up for an MBA after I realized I didn't have the confidence and needed time to develop in an environment that encourages immersion and discussion of these topics.

Not everyone needs to do this. But those who do, like me, should do an MBA.

A large part of getting the MBA is the piece of paper saying you have one, and another large part of it is the network you form while getting it. Things you can't really get online.