Yeah, it really is not. Mapbox Vector Tiles spec came out in 2014, and they've been absolutely standard across all (non-government) web mapping for at least the last 5 years.
Could you explain why you say that? My understanding is that rasterized tiles are only a graceful degradation when necessary in MapKit, while vector is default, as the behavior and experience would indicate.
I was referring to using custom vector tiles like the ones in the post with MapKit, not Apple's tiles. The MKTileOverlay is the only way to do it and it only supports bitmap tiles.