Looks like Firefox's reader view fixes it, I'll just need to get in the habit of using that instead of the Kill Sticky Headers bookmarklet as things catch on and circumvent it... https://alisdair.mcdiarmid.org/kill-sticky-headers/
I can only assume the thought process of whoever writes these social bars is "People are hiding our share buttons instead of clicking them! MAYBE IF WE SHOVE IT IN THEIR FACES REPEATEDLY THEY'LL LIKE THAT BETTER AND WANT TO SHARE!"
Gruber sums up my feelings nicely: https://daringfireball.net/2017/06/medium_dickbars