Its all but replaced Thought Scour as the cantrip of choice for blue graveyard decks, and for good reason
Moreover, if your Army cannot be a target for some reason, you should not worried, because there are no targets in Amass: you choose a creature with an Army type among creatures you control
When you consider that single-target exile removal is very much costed at six or more on creatures and artifacts, it becomes more reasonable to assess the card
For most of its history, Commander has been about deck-building as an individual journey, and the foibles of individual budget, opinion and card availability ensured that barely any two decks were alike
As I touched on above, we can potentially choose from a wealth of different subthemes when upgrading the deck, or even combine them freely