RBAC is absolutely a practical security control, even for non-commercial users. Least necessary privilege is not a checkbox, it will 100% save your butt in a breach by limiting blast radius.
Let's say you work at a company that uses Elasticsearch. Let's say you're running a newspaper and you've got your logs in elasticsearch. Let's say one of your reporters ends up getting chopped up while they're visiting the Ostrich embassy to get a marriage license. Now let's say you're then asked "who looked at the logs of the CMS who searched for and found the IP address that was used by that reporter on October 1st 2018"
That example, purely hypothetical, is an example of "security" but not the typical security you'll see in some open source application -- it's an enterprise "compliance" feature that won't be trivial to implement and will be judged not just on completeness but on user interface, ease of use, ease of implementation, etc.
"security" means different things to different people
