I see. From the description it's quite obvious that ZFS handles most of the fault cases automatically. Still admins might want to force it to recheck all the blocks, this command achieves exactly that. Frankly I don't know what exactly fsck does and I guess it's different for every FS. For ZFS scrubbing seems to be an adequate alternative.

Hence if anyone asks you whether ZFS has fsck it's easier to say yes it does and it's called scrubbing.