Not so.
O'Reilly stopped selling those on its own site, but they still produce them and sell them through retailers.
For example, ebooks.com carries them in both DRM-free ePub and DRM-free PDF [1].
When searching at ebooks.com, you can add "Format:18" to your keywords to search for DRM-free PDF, or "Format:17" to search for DRM-free ePub.
[1] https://www.ebooks.com/searchapp/searchresults.net?sortBy=So...