The assumption that no key sent a BS character allowed control+H to be used for other purposes, such as the "help" prefix command in GNU Emacs.
ðɪ ɐsˈʌmpʃən ðæt nˈoʊ kˈiː sˈɛnt ɐ bˌiːˈɛs kˈæɹɪktɚɹ ɐlˈaʊd kəntɹˈoʊl plˈʌs ˈeɪtʃ təbi jˈuːzd fɔːɹ ˈʌðɚ pˈɜːpəsᵻz, sˈʌtʃ ɐz ðə "hˈɛlp" pɹˈiːfɪks kəmˈænd ɪn dʒˌiːˌɛnjˈuː ˈiːmæks.