Synchro of Unity is very good when chaining card effects together to get those Synchro cards on the field as quickly as possible
It was one of the first Archetypes in all of Yu-Gi-Oh, and for good reason
If this card is Normal or Special Summoned: You can Set 1 "The Phantom Knights" Spell/Trap from your Deck
Today, the Shaddoll strategy relies heavily on its best control card because El Shaddoll Winda only allows one special summon per turn while it is on the field, making it a nightmare for some decks to deal with
Within those deck types, having cards that can fetch your desired Ritual monster or spell are pivotal for success, such as Manju of the Ten Thousand Hands
Yet the card never truly went away, as new fusions like Chimeratech Fortress Dragon and particularly the arrival of Xyz monsters once again boosted its popularity