What exactly do you feel like you are missing out on by not using facebook? And whether a linkedin account is beneficial is dependent on what kind of work you do.
This is a road to madness. If every time you wouldn't understand something you would just plunge into the material and get familiarized you would do nothing else for the rest of your life. I think Eno means managing ignorance in the way of making a decision on when to stay ignorant (whilst being aware of your ignorance) and when to learn and hence "fix" this ignorance.