Active Skills that secondarily create Minions, cannot be supported by Minion Support Gems

As title reads: even when a skill or its supports can cause it to create minions, that skill is unable to be supported by skills which affect those minions.

The first example I can think of is actually the first skill gem you get as a witch: Unearth. Despite creating minions, you can't support it with any minion supports, such as Last Wish or Death March. This feels rather unintuitive for an iconic Witch skill.

More recently added to the game: Skittering Stones. This new Strength support gem creates pairs of little guys that live for a duration and scale based on your strength. However, they can only support skills that create "shatterable earthen objects", which is I believe 4 skills; this already drastically limits the possibility for using it, but since they cannot be supported by any minion support gem, and their Strength scaling is an additive increase, they are borderline unusable.

Bump.