OSM Carto is just one of (currently) 7 map styles visible at https://www.openstreetmap.org . There are many, many more elsewhere.
I don’t buy that it is just a style as any other, we tell this story to everybody but it isn’t the reality. The other styles on osm.org are not comparable to OpenStreetMap carto which is the default style on the project frontpage (most visitors do not change this) and unlike the others is rendered and distributed from OpenStreetMap-Foundation paid and controlled servers.