Feature request from bansavage, posted on GitHub Jan 25, 2018
I would like to display out-of-stock products at the end of my category pages. This option does not exist in neither the system configuration nor store configuration. There is also no effective way of programmatically accomplishing this task.
Also, please note that this issue has been documented since November 2016 and has still not been resolved. This has been and is continuing to be a major issue. (https://github.com/magento/magento2/issues/7589)
Comment from magento-engcom-team, posted on GitHub Jan 26, 2018
@bansavage, thank you for your report.
This seems to be correct Magento behavior. Please refer to the Community Forums or the Magento Stack Exchange site for advice or general discussion about this.
Otherwise you may submit Pull Request with the suggested changes.