By the time so-called "glass TTYs" (later called CRTs or "dumb terminals") came along, the convention was so well established that backward compatibility necessitated continuing to follow it.
baɪ ðə tˈaɪm sˌoʊkˈɔːld "ɡlˈæs tˌiːtˌiːwˈaɪz" lˈeɪɾɚ kˈɔːld sˌiːˌɑːɹtˈiːz ɔːɹ "dˈʌm tˈɜːmɪnəlz"kˈeɪm ɐlˈɔŋ, ðə kənvˈɛnʃən wʌz sˌoʊ wˈɛl ɪstˈæblɪʃt ðæt bˈækwɚd kəmpˌæɾəbˈɪlᵻɾi nəsˈɛsɪtˌeɪɾᵻd kəntˈɪnjuːɪŋ tə fˈɑːloʊ ɪt.