I'm trying to understand the following statement:
Any simply connected $\mathbb{Q}$-simple (algebraic) group has the form $\mathbf{R}_{F/\mathbb{Q}}(G)$ where $F$ is some field containing $\mathbb{Q}$, $G$ is an almost simple $F$-group and $\mathbf{R}_{F/\mathbb{Q}}$ is the restriction of scalars functor.
This statement appears in the book 'Algebraic groups and number theory' by Platunov and Rapinchuk on page 77. It seems to be stated there as a kind of trivial observation. To me it seems like a non-trivial fact for which I'd like justification for. I can imagine trying to justify it by considering the action of the Galois group of the field extension (assuming it is Galois) and showing that the action on the factors of a $\mathbb{Q}$-simple group must be transitive. Is this the right idea? Or is there something simpler?