It is highly recommended to use mineral oil for 1000 and 5000 oil change to allow the engine to fully run in properly before starting on synthetic oil at 10,000km.
Premature use of synthetic oil can affect the running in process and damage the engine in the long run.
What facts or data proven that so called premature use of synthetic oil can affect and damage engine?

I can use 0w20 synthetic or semi synthetic oil for 1000Km or 5000Km service if I rich enough. As most of us know that synthetic can last for 10,000km and more expensive, therefore general usage would recommend to use mineral oil as the usage is only 1000km and subsequent 4000km, if using synthetic oil will be a waste.
Do you know performance car come with synthetic oil from factory? So do you now know the reasons?