(Sorry for the glut of questions lately) Did the Tumblrpocalypse lead to a whole lot of blog deletions? I find quite a few "page not found" links when reading older blogs such as yours, and I'm not sure how much the Tumblrpocalypse contributed to that - even for SFW bloggers.
I don’t think Tumblr itself deleted very many blogs. What happened is that Tumblr implemented an algorithm to try and shut down how much porn there was going around. It was more in a bid to appease Apple and Google, who didn't like housing a mobile app that had easy access to pornography. But Tumblr's automatic detection method was sloppy and incorrectly flagged a lot of blogs as being pornographic that were actually perfectly safe.
What happened to blogs that the algorithm flagged as being NSFW is simply that they got put behind a special filter. That filter effectively made those blogs invisible -- they won’t normally show up in your dashboard feed and they don’t appear in search results.
From what I remember, the only way to view a flagged blog is to visit the URL directly in a web browser, because they are blocked completely in the mobile app. You also have to have a tumblr account and be logged in, because the website will give you a “this content is not suitable for minors” disclaimer that can only be clicked through if you’re logged in.
When that happened, a lot of people abandoned the site in droves. It didn’t matter if their blogs were flagged or not, a lot of them left out of solidarity for artist friends or whatever. The worst that happened to most of them would’ve just having their blog flagged. But they deleted their accounts by choice, in protest.