I knew people using Direct Connect at my university, but haven’t myself. It’s not what I’m aiming for, no.
My personal Syncthing use just naturally led to a structure where it would be a useful addition. Exchanging pictures and documents with family members (partly intersecting groups, Dropbox alternative), recommending it to other people where (except myself) one to four people work on a project with shared data for some time, and sharing project data among co-workers for a small business. Each person has one to three devices, plus I run two NAS servers. So my overall device and folder count is above average, yes. But most people in those small groups have less, yet they would benefit from getting a hint when I set up a new laptop for myself, or add a smartphone to the mix.
My terminology is “cluster members” from kind of an admin perspective, but the goal is not having to tell two people: “I put a text file in this folder, please copy each others’ ID from there to enable direct sharing among you”. Instead I could tell them to open the GUI, edit the folder and follow the suggestions on the Sharing tab. Whatever other uses they might have put Syncthing to for their independent personal needs.
Adding someone new to my laptop’s Syncthing and on the NAS after I already did the initial setup with them on my smartphone will also become easier because the IDs are already listed, one click away instead of copy-and-paste.
It kind of follows the spirit of listing locally discovered device IDs when clicking “Add Device” by the way. Very useful IMHO.