We're doing selective rendering with MapBox Light, which is deeper in cities. For this, it's better to have always-there zoom levels. Otherwise you grapple with the deep, deep problem of someone panning from a high-zoom area to a low one, or using an API like Leaflet programmed to zoom to a level. Unless you control the API and have a zoom-depth-api like Google, having a map with highly variable max zooms isn't an easy call.