No, we start with 1 or 2 Stargates but in late-game when resources are more available multiple production structures are a necessity.
Just think in PvZ after a big battle Protoss lost 1 Mothership, 6 Carriers and 4 Voids. Without multiple Stargates (KingCobra sometimes has as many as …7-8) one can’t replace the Golden-Armada fast enough.
Please deal with your race (continue whinning), Protoss is too difficult for you to understand.