 What is one limit all kinds of OA put on user freedom?
In any case, we can be more specific about which access barriers OA removes. OA removes price barriers. But at the same time, all three allow at least one limit on user freedom: an obligation to attribute the work to the author. The purpose of OA is to remove barriers to all legitimate scholarly uses for scholarly literature, but there’s no legitimate scholarly purpose in suppressing attribution to the texts we use. In principle, any kind of digital content can be OA, since any digital content can be put online without price or permission barriers. OA is made possible by the internet and copyright-holder consent.
 There is an obligation to credit the work to the author.
 A constraint on library privileges.  A limit on text mining.  A constraint on reproduction and distribution.  There is an obligation to credit the work to the author.