I think I figured out why I slowed down so precipitously on my blog posts. It's not because I moved over to social media like I thought I would - I'm not posting there, either (actually, the thought of posting on social media makes me feel apprehensive these days).
Nope - the reason is that there are no physical thumb keyboards on any smartphones that I would want to have anymore. I can type 80 wpm on a real keyboard when I'm good shape, and I can handle the tiny thumb keyboards very well, but I'm close to hopeless with the onscreen touch keyboards.
In 2004, when I started this blog, I was using a Treo smarphone with a keyboard - I did some hacked extensions to to bloxsom (the blog software I'm still using) so that I could easily posts pictures and some accompanying text from my phone. It was so easy that I did it very frequently. Once the Treo went the way of the pterodactyl, I hung in there for a while with Android based phones that had slide-out keyboards, but those fell out of fashion as well, and here I am, typing on a macbook :(