Interestingly, I also "business-ified" my Instagram account and also saw post engagement drop to essentially nothing. (And I use Instagram a lot, and have a good feel for how any given post will be received.) I noticed it immediately, and wasn't happy at all.
I came to the same conclusion you did: that a "business" instagram account requires constant input of money in the same way a business Facebook page does, and decided I didn't like that one bit. So I turned it off.
As for completely excising the entire Interwebs, I see the point, and have done it, but I'm not terribly fond of it. Given my career choices, it's pretty obvious I have at least a moderate case of narcissism that manifests itself in me wanting to show others the dope shit I'm doing. Without the Intardwebs, well... if a tree falls in the forest etc.
Yes, I get that. I enjoy the interaction and getting feedback on my own creative endeavors. It’s just that every now and then I feel a need to kick the monkey off my back for a little while.
I’ve also noticed that when my brain doesn’t have a constant morphine drip of content fixes... without a constant source of passive entertainment... it (the brain) seems to kind of wake up and starts entertaining itself with new ideas and wild imaginings.