It could be a way to distinguish GT Sport's online tournaments from something like GT Academy. To participate in the Academy, you needed to be above a certain minimum age, have some prior real-world racing experience, and so on, meaning that realistically only a small number of people could be in with a chance of joining the Academy (and a smaller fraction still being able to proceed through all of the stages of the training).
However, GT Sport's take on this is the actual competition is held within the game, from start to finish, and stays firmly grounded in the virtual world, meaning that theoretically, anyone old enough to understand how to use a DualShock 4 or racing wheel could be the champion the FIA crown at the end of it all.