A few things:
- Backing up settings somewhere: there is a facility in NVDA that will let add-ons react to settings save action. Using this facility, it is possible to create an add-on that will save settings to somewhere else so you can restore it later. However, this isn't effective when NVDA is exiting as add-ons will be gone by the time NVDA closes.
- Configuration profiles: one issue I have (as I also noted in a subsequent GitHub issue) is configuration profiles. Suppose a setting is introcued to alert users of settings changes when NVDA exits. What if the user exits NVDA while a profile other than normal configuration is active, and what if multiple profiles were edited? You might end up with a situation where you would save the wrong profile and discard the correct profile in regards to saving settings.
- Unexpected NVDA restart: suppose you change an important setting needed to resolve an issue you are having, and told NVDA to not save settings automatically. But suppose somehow NVDA restarts unexpectedly - perhaps an add-on has crashed NVDA (it is possible to crash NVDA with add-ons if they override functions provided by NVDA somehow or a DLL file performs unexpected things).
To focus on the original question at hand: a while ago it was proposed on GitHub and elsewhere to create a cloud backup feature to NVDA - that is, back up settings to the cloud and restore it later. The responses to this centers on possibility and logistics: it is possible to exchange data over the Internet, but how will NV Access keep track of which settings belongs to whom.
As for a related discussion on saving settings by default, if you think about it carefully, modern apps (Windows Settings, for example) will apply changes immediately. Even when we think about classic apps, save dialog applies to main content, not settings (tell us if changing view settings in Notepad without writing anything prompts a dialog to save settings). Even in Windows, unless you edit startup options or run Windows Preinstallation Environment (WinPE), settings are saved to Windows Registry even after you click OK to change settings. I won't go furtyher into this as the original question deals with backing up things, but I hope you get the idea.