> The OSM datamodel still revolves around a single datafile containing all data. You could make an argument that this is not true: at an implementation level,

> The OSM datamodel still revolves around a single datafile containing all data. You could make an argument that this is not true: at an implementation level, the more fundamental OSM data model is a really big PostGIS database, which has the appropriate indexes to let you query whatever subsets you want. The big flat-file XML/PBF dumps are just one way that this data is exposed. You can also query the API for objects within a bounding box (and thereby benefit from the DB indexes), or you can use the daily/hourly/minutely incremental diffs to run your own database replica.