Hi all,
The issue of readers not being able to view links to library content is definitely one we're aware of. Ultimately we agree with Rebecca in believing this to be net-positive, in that Wikipedia can now summarise previously inaccessible information, but we absolutely do want to encourage editors to use open access sources wherever possible.
In the new search feature we included an Unpaywall integration which shows links to free-to-read versions of search results alongside the paywalled links wherever possible. This means that editors can choose to cite that version alongside or instead of the 'primary' URL where appropriate.
Additionally some library partners (e.g. Newspapers.com) have functionality by which editors can link to 'clippings' of the source which are free for readers to view. We've been encouraging other publishers to include such features and have even had a few conversations about the potential of making links from Wikipedia to paywalled resources free-to-read based on referring URL, though that's a much harder conversation!
Also worth noting we had a conversation about this back in 2015 and wrote a blog post on the topic you might find helpful:
https://diff.wikimedia.org/2015/09/16/open-access-in-a-closed-world/Best,
Sam