It's not only "two app stores", it's actually applied to everything - literature, art, movies etc, etc. There's always a "mainstream" which has more mass-market

It's not only "two app stores", it's actually applied to everything - literature, art, movies etc, etc. There's always a "mainstream" which has more mass-market appeal, and then there is something more deep and complex, but it only is of interest to a smaller percentage of, well, "customers".