You've all been so wonderfully patient and helpful with all of my questions that I wanted to share a little about what I'm doing here.
For many years, I was a one-person IT department at a small engineering firm (between 20 and 100 people, depending on project load). At some point, we created an intranet using Plone 3 as our platform, and it saw heavy adoption and use. It really became the "go-to" for all of our corporate information, procedures, standards, etc., and replaced all of the paper and filesystem-based resources we were using previously rather well.
Some years ago, we were acquired by a significantly larger firm, with their own IT staff. I've been in a branch office IT support role since. One thing that became apparent is that their internal documentation is rather ad-hoc and, frankly, kind of a mess. They had a SharePoint-based intranet that contained virtually no information and saw very little user adoption, and to which our access was very limited. In the intervening years, we've continued using our existing Plone 3-based site, due to the lack of any other viable option.
There's currently a big effort to better integrate our offices, and as part of that, they've decided to create a new intranet and centralize their documentation and resources there. We've settled on Plone 5.1.6 for our platform. They require a lot more customization and specific capabilities (not least of which was multi-language, since they're located in Quebec, and LDAP authentication since their security model is much more complex), and had a lot of demands for custom theming and corporate branding. While the site hasn't launched to the users yet, we've had a lot of success with getting the results we want from Plone so far! (Sadly, I can't link the site, since it's internal.) I've conducted a few training sessions with other relatively-non-technical users who will be authoring content for the site (especially users in HR), and they've been surprised and pleased by how easy it is to use.
Since I'm not a developer by trade, and we did very little (more or less zero) customization of Plone 3, these forums have been invaluable in assisting me in meeting those goals, so in addition to sharing a real-world use case, I wanted to thank everyone for your patience and kind help.