Neither did MS-DOS until version 2.0. Both CP/M and MS-DOS 1.0 were targeted at computers which almost exclusively utilized only small capacity floppy drives fo

Neither did MS-DOS until version 2.0. Both CP/M and MS-DOS 1.0 were targeted at computers which almost exclusively utilized only small capacity floppy drives for which a hierarchical filesystem made little sense. CP/M was already basically dead by the time hard drives became cheap enough for the type of systems CP/M targeted. If it had not been then certainly support for a hierarchical filesystem would have been added.