The thing is, if you look at that list, you will notice its not one coherent mass of goodies playing against the scions. The presence of Danclavien alone divides the list in two masses that not only refuse to cooperate, but indeed fight each other bitterly. Lintronea for instance rather prefers to walk with warlocks than sylvans, and sylvans quite happily turn on warlocks, even in the presence of scions.

Btw, I've had my fair share of being alone against a hoard of scions, as I am sure everyone else in that list. It probably has to do with time of day (and the lich/krivohan effect).