You don't need two PC's to stream to be a successful streamer, but it does have 2 big advantages:
Calum 'itemm' MacGillivray is a professional Fortnite player for E11 Gaming. He can also be found streaming on Twitch.tv regularly.
For gaming, itemm uses a Intel Core i7-9700K CPU with a NVIDIA GeForce RTX 2070 GPU. He uses a ASUS ROG Strix Z390-E motherboard. itemm uses CORSAIR Vengeance RGB Pro 16GB memory.