I have read today a ticket in which there are some struggling with PHPStorm even the 4 EAP version to autocomplete some FQCNs methods etc.
The trick has long been lived in the community and is doing just the following:
/** * @var $myProperty \Behat\Mink\Behat\Mink\Session **/ $myProperty->getCertainMethod();
It could be tedious and you could blame one or the other but it seems it was a convention. The idea of why the docblock is like that comes from a practice of just conveying the class information that the parameter is relying on. Until PHPStorm adopts this or you change completely the symfony2 standard then someone would keep on bearing this.