While strictly speaking I do have both Twitter and Facebook accounts, I don't associate them with any other website. I never, ever press the "Like" button on anyone's site; if I want to share a page on Facebook, I post its link on my wall.
This is largely because I do not want to be tracked, and that I am working hard to defeat analytics. I regard both web and mobile analytics as profound invasions of my privacy.
I don't have any problem at all with Medium or anyone else analyzing their own web server logs. What I don't want is for any one site to correllate my activities, with my activities at other sites.
I would be quite an active contributor to Medium discussions if I could register directly with Medium, without associating my Medium accounts with any other sites.