I guess they were aware how terrible and unpopular injections are for patients. These weren't the days of micro needles...
What is this belief founded upon?
Disposable syringes and detachable needles have been around for over 50 years. We had 6mm needles in the 80s.
Evolution of Insulin Delivery Devices https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7261311/
The fear associated with specific phobias is by definition extreme, unreasonable, and irrational. If you could understand it rationally, it wouldn’t be a phobia.