These are indeed good reasons for BLOBS over files: concurrency and remoting.

Another is transactions over multiple operations, on multiple files/tables, on multiple servers. This is very difficult to do with filesystems. You need to do 2-phase commit, backup directories, etc. With BLOBS, operations are part of the normal transaction.

Another is consistency: the BLOB fields are handled the same way as the rest of the data. No need to think tables & files. Just tables.

Besides, BLOBS are not as difficult as they used to be. If you use something like Tangram, and your BLOBS fit in memory, you don't even have to think about it. You use them like regular fields.