[0]: https://docs.syncthing.net/users/ignoring.html
> The .stignore file itself will never be synced to other devices, although it can #include files that are synchronized between devices.
So you might have a synced work folder, where some large but unimportant throwaway files will be created on Host A, you exclude them to avoid having them replicated when syncing to your Host B (and C, D, E, ...). But then, ignore rules don't sync so... surprise! those throwaway files when generated in the other Hosts will show up in A and everywhere else.
Am I being too unreasonable here? Yes, you can sync a common ignore file and #include that everywhere. But the idealistic way I see computing, that's a totally superfluous step that users should not even have to worry about doing. The kind of subtle technical detail that makes me agree with the phrase "too complex, unpolished and confusing".
Still, I use Syncthing every day. I think it's great. But I'm a developer and Git taught me ways about the logic and behavior of writing ignore files; it's not an apt solution for "less able, cognitively impaired, or perhaps very young" people.
The issue seems to be recognized [1]. But what can I say? the improvement proposal was outlined in 2015 and it's still unresolved 6 years later [2]. I wouldn't hope that it will get much more approachable for less technical people anytime soon.