The SQLite "faster than filesystem" page is specifically about reading small blobs where the overhead of individual filesystem calls (open/read/close per blob) exceeds SQLite reading from a single already-open file. Once you're talking about reading one big JSON file sequentially, that overhead disappears and you're just doing a single read - which is basically the best case for the filesystem and the worst case for SQLite (which still has to parse its B-tree, check schemas, etc).