I don't share this experience. I've been running Time Machine for years now on a Samba share for multiple Macs and if anything I've only seen an improvement. Years back I would regularly get a corrupted Time Machine sparse bundle that had to be recreated (or I would restore a previous ZFS snapshot and it would continue of off that), but it also ran over AFP back then I think, not SMB. Lately I've not have had any of these issues on any of the machines. I do have specific flags enabled in the smb.conf file that are recommended for Time Machine backups.