We need to recognize that when folks talk about add-on settings, it can either mean the settings interface or where settings are actually stored. I'm assuming the former in my reply below:
In theory, add-on authors are supposed (or rather encouraged) to present add-on settings interface in NVDA Settings screen. Not all add-ons do this for various reasons:
- Add-ons come with additional screens required to use the add-on. The best example is Remote add-on where the add-on creates a submenu inside NVDA Tools menu to house not only add-on options screen, but also menu items to handle remote connections.
- Add-ons provide different interfaces for different purposes. The best example is Add-on Updater where the add-on does offer a settings panel as part of NVDA Settings screen in addition to adding a menu entry in NVDA Tools menu for checking for add-on updates. I (the author of this add-on) did it intentionally to let users configure ad-don settings from NVDA Settings interface while opening Tools menu to check for updates.
- It is becoming harder to track who is developing what and keeping up with changes. To keep the thread short (hopefully because going into compatibility discussions may lead to a repeat of what we saw in May and June), suffice to say that add-ons community is still keeping in touch with add-on authors, at least authors with known contact information. I'm hoping that a new mailing list NV Access has just launched could make it easier to inform folks about keeping up with changes. As Brian V noted several times and as I have demonstrated, add-ons can become unmaintained or authors seek new maintainers.
In short, while I understand the reasons for the initial suggestion, I'm afraid that reality tells us otherwise. Hope this helps and clarifies a lot.