I'd only recently heard of FOMO. Being a retired introvert, it's not surprising that term was new to me. I could imagine its crippling effects in the professional sphere, especially for entrepreneurs. Even while I was still working, it wasn't really a "thing" that had any impact for me. It might have if I were higher up in the chain, someplace I'd known since my 20s that I had no desire for.
The job where I was the happiest was the kind where my supervisor gave me my task and left me alone. I went through days of almost no interaction with others unless I needed information, or if someone wanted my help.
Outside of my professional life, things I most enjoyed involved stuff I had at home. I always preferred quiet environments. After a major depression in 1989-1991 and a brief relapse in 2003, I became extremely noise-sensitive. Most activities that people are afraid of missing out on, I DO want to miss out on!
I have accounts on Facebook, Twitter, Tumblr, Pinterest, Instagram, and maybe one or two I've forgotten about. I created these because I was told that I needed to. I participate in some crochet and writing Facebook groups. I haven't read my Twitter feed in years. I'm not even aware of what I might be "missing". I'm content to keep it that way.
I don't care what people think of me, so not doing what they insist that I "really HAVE to do" makes no impact. I know what is important to me, what I need to do, and what I want to do. I don't need anyone to tell me what these are.
I agree that we should check in with ourselves before reacting to notifications designed to manipulate your emotions. The only thing is, I don't GET these notifications, and I'm so UNemotional that I wonder if I even have what it takes to be a writer.