I think Apple's general idea with this was to recruit extension developers into Apple platform development in some capacity, since paying that $100 also gets yo

I think Apple's general idea with this was to recruit extension developers into Apple platform development in some capacity, since paying that $100 also gets you access to the iOS and Mac app stores. It's probably not that unreasonable of a thought; any developer capable of creating a browser extension could also probably whip together some kind of electron/touchgap web app and publish it on iOS and/or macOS. Conversely, they may want existing iOS and Mac devs to be the ones creating Safari extensions rather than the current crop of multi-browser extension developers. This may be their way of trying to recreate the Mac's propensity to be a host to unique, platform-exclusive apps — in other words, they want Safari to have several prominent exclusives instead of just the same stuff you see everywhere else. Regardless of the motive I think it's safe to say that it isn't working out as they've planned.