On the back of a £20 note: “The division of labour in pin manufacturing: (and the great increase in the quantity of work that results)” Adam Smith 1725 – 1790.
Ignoring two things – that this also involved mechanisation and is concerned with manufacturing – economists and, subsequently, management theorists took specialisation to be universally advantageous.
Work specialisation is just one aspect of ‘scale’ designs; designs built on the belief in economy through scale.