In all honesty, though, Dismiss into Dream is a great concept. But being 7 mana, it simply was so far above the curve to even begin to be considered in Constructed and most players truly did Dismiss this card. However, it’s still a fun card to consider for your next Commander brew. It does affect all opponents. Has anyone actually used this? Yes, indeed. The most popular case is with the incredibly broken Commander, Derevi, Empyrial Tactician. With Dismiss into Dream in play, anytime Derevi goes to tap an opponent’s creature, the creature’s controller must sacrifice it. This is pretty awesome, since indestructibility doesn’t help and destruction replacement effects don’t work, either.
Other Commanders that have used this Enchantment include Keranos, God of Storms, Niv-Mizzet, the Firemind, and Roon of the Hidden Realms - all of whom have targeted abilities. Some Melek, Izzet Paragon decks have run it to make his instant and sorcery spells do even more work. Some Thassa, God of the Sea decks have run it to, mostly just to have another Enchantment, but also to make targeted blue bounce spells into sacrifice a creature spells.
The only reason we haven’t seen it in more decks? Seven mana is a lot, no matter how good your effect is. There are just bigger, better bombs. But when you can make this good, it’s pretty funny - for you, anyway.