against the fixed position

Daring Fireballs has had some anti-"dickbar" ranting lately (social media "share me share me!" widgets, often fixed in place -- this one on best practices for sharing (tl:dr; emphasize sharing via the site the person CAME from) has a side note

You read that right: adding a locked toolbar to the small-screen experience shortened sessions and reduced page views. The very small increase in share-button usage was far outweighed by reduced site usage. (I can't explain why this is the case, but I've seen it elsewhere with locked toolbars, too. They chase small-screen users away.)

That jives with some "surprising" A/B results we found at my job, where we though permanent "Contact" buttons at the bottom would get more hits- some of our competitors were using them, so they might be a good idea, but apparently irritation from users at the sacrifice in free screen real estate overcomes the "hey look at this!" factor.