Yes, this is the method of Al Qaeda, but also of other terrorist groups :
With diffuse propaganda, they target the most vulnerable people but it is very hard to arrest the leaders because they are not in the same country and it is harder to prove that the people "representing" the terrorist groups in the attacked country were involved.
It is important that those agressors are caught alive because their interrogation will help in understanding the process and maybe, if we catch several of them, and by comparing what they say, we can catch the "head".
But internet is not guilty on its own, this kind of methods always existed, and there are multiple examples of this, it simply made things easier and more efficient with a larger audience.
Anyway, the agressor of the french soldier was arrested too, and the soldier is out of hospital.