Actually, you are quite wrong.
Nestorius denied the use of the word Theotokos, as you do here, and was condemned for Heresy.
Theotokos means ‘God bearer’, and is where the term ‘mother of God’ originates, and was in use long before the 5th century.
Seems to me the source was accurate.
GOD BEARER
is
not
the SAME as
MOTHER OF GOD.
The implications are far different.