Whaat? Good grief you people are gaga about the word synthetic. Mono-grade lubricant users are compared to global warming deniers and the Flat Earth Society.
Now if you believe in global warming, then why is engine oil going the other way?
Back in the day, 10W30 was the standard multi grade. Truckers wanted thicker and invented the wildcat grade 15W40, likely by mixing 10W30 with SAE 50.
Suddenly 10W30 isn't good enough, because in some climates 5W & 0W cold start protection is need in the winter months. Note; 10W is close to where 5W was 20 years ago.
Not good enough to have seasonal oil changes anymore, cold climates get 5W & 0W year round.
Not good enough that cold climates get 5W & 0W year round, everybody gets it, hot or cold.
This plays right into the need for synthetics and why there are no 15W20 or 10W16 oils on the shelf.