Most card games do that and it generally makes for better-rounded decks
As with Deny the Divine, its lost some utility, but that makes sense when considering how bonkers powerful War of the Spark was
The magic is in the design, the plastics still yours
The Green Tutors Between Green Sun's Zenith, Chord of Calling, Invasion of Ikoria, and Finale of Devastation, there are tons of X-spells in green that tutor creatures directly into play, some pulling from the graveyard, too
Play Rule #13 states: Abilities which refer to other cards owned outside the game (Wishes, Spawnsire, Research, Ring of Ma'ruf) do not function in Commander without prior agreement on their scope from the playgroup. Therefore, Spike is twice banned in Commander, and even if Unstable were allowed, Spike wouldnt be able to be played