If that is a statement, then Yes, that is what I was saying.
If it is a question, then maybe this additional clarification helps :
IG uses CFDs for say the Nasdaq Future. With that, they can create their own price. The NQ (you will see with your personal PRT) is still underlaying, but in a super vague fashion.
Besides this, IG uses her own “community”. This is how they can also let you trade the Nasdaq e.g. in weekends.
It is thus not about the backtest data (this is representative for either situation within itself) – it is just that you can’t make a strategy for the personal PRT which will work under PRT-IG.
Clear a little ?
… But maybe I am not understanding you for 100% …