You don't need two PC's to stream to be a successful streamer, but it does have 2 big advantages:
Blaž 'K1nzell' Lešnik is a Slovenian Fortnite player who previously played for Team Atlantis. He is currently a Twitch Streamer.
For gaming, K1nzell uses a Intel Core i7-8700 CPU with a NVIDIA GeForce RTX 2080 GPU. He uses a GIGABYTE Z370P D3 motherboard. K1nzell uses HyperX Fury Black 8GB memory.