They were coined before the development of systematic names, and have been retained due to familiar usage in industry.
ðeɪ wɜː kˈɔɪnd bᵻfˌoːɹ ðə dɪvˈɛləpmənt ʌv sˌɪstəmˈæɾɪk nˈeɪmz, ænd hɐvbɪn ɹᵻtˈeɪnd dˈuː tə fəmˈɪlɪɹ jˈuːsɪdʒ ɪn ˈɪndʌstɹi.