Yup. I've taken some MBA classes, and one (in retrospect obvious) thing I latched onto is the idea of opportunity cost: you can never do everything you are capable of doing, and each thing you do comes at the expense of something else. So, focus on doing the things that (depending on your goal) are most fulfilling and/or most profitable.
Amusingly, grasping that concept was a big factor in my decision to put my MBA degree on hold...
There is one other reason to do things: you cannot trust anyone else to do it. Fullfilling and/or profitable are hopefully the only ones that apply, but sometimes you have to do something because the risk is too high...
An example of how it could apply is if shopify were to "go down" often thus driving your customers to your competitors that roll their own solution that has good uptime.
Amusingly, grasping that concept was a big factor in my decision to put my MBA degree on hold...