How is understanding that clicking on a face in medium does one thing any different than understanding that clicking on the header in a tumblr does something else?
The equivalent of a Tumblr logo on Medium would be their "M" logo. When you click that, you end up on their front page, and not on my profile, which is what you should expect.
You are partially correct, this implies that the user understands the basic behavior of the web and expects my photo to lead to one place and "M" to another.
The point, correct me if I'm wrong, of your post was that a company's logo on their Tumblr blog should go to their own website and not to the root of their Tumblr blog. Yet, because your blog is on Medium it's ok that none of the titles go to your homepage?
I want to find out more about you. I click on your picture, it takes me to a profile on Medium, which links to your about.me profile and your twitter profile (and mentions a twitter handle for Scoutize). I then have to click through those to find actual links to your personal blog and Scoutize. Why are you ok with this interaction but it's not cool for a company to do it with Tumblr?
Like I said, going from my face to my Medium profile is exactly what should be expected. Much like going to your profile on pretty much any website out there.
If by clicking on the M button I got somewhere other than the Medium front page, that would have been a valid argument for you, but I do get to Medium front page, so it isn't.