Hazel can make a Squirrel army, but the Odd Acorn Gang can make a Squirrel army win
If a card effect specifically says it can damage/banish/return to hand a location, or any card type on the field, or just says do damage, then yes
Its vague ability encourages a fun deck filled with these types of cards and I predict Thurid will become quite popular because of that
They are powerful, however, and will almost always improve a decks performance
EligethEligeth does have the Partner keyword which allows for a more versatile deckbuilding experience through another, non-blue partner commander, but MatoyaMatoya is leaps and bounds superior to EligethEligeth when viewed as the single commander for a mono-blue deck
Rares are in their own box as a matter of convenience when trying to arrange trades