From the superb, just-released COPIM report on collective funding models, which interviewed academic librarians:
According to some of our respondents, the funds potentially available to support library membership programmes were also being squeezed by the rise of transformative [i.e., read-and-publish] agreements. These are agreements between libraries and publishers to turn subscription expenditures into funds to support open access publishing. As one of our respondents noted [...] in some cases major commercial publishers are using transformative agreements as a way of increasing the total amount charged to libraries, by adding open access publishing costs on top of normal subscription costs. The effect, our respondent suggested, was to drain the pool of money available for supporting forms of open access outside of these agreements, including library membership programmes.
This read-and-publish funding lockdown is happening right now—in dozens of mid-negotiation deals slated (it's safe to assume) to be announced over the next six months. We're running out of time.