Firefox users who either dislike the requirement for permission on all sites, or don't want an additional extension: know that you can achieve about the same with a few lines in your userContent.css [1]

  @-moz-document domain(medium.com), domain(backchannel.com), domain(hackernoon.com), domain(mondaynote.com), domain(artplusmarketing.com), domain(codeburst.io), domain(logrocket.com), domain(slack.engineering), regexp("https?://medium\..*") {.js-postShareWidget, .overlay, .overlay--lighter, .postActionsBar, .js-postActionsBar, .metabar, .js-metabar, .postMeterBar, .js-meterBanner, .highlightMenu, .highlightMenu--active, .popover, .js-popover, .popover--dark, .butterBar--privacy, .js-stickyFooter {display: none !important;}}

Obvious gotcha: incomplete list of domains, now you have to add medium domains when you meet them and restart Firefox.

[1] http://kb.mozillazine.org/index.php?title=UserContent.css