Let me quote the almighty Google on this one…
Working with gamers and streamers as your brand influencers can be your catalyst for growth. These personalities can help introduce your brand to a broader market, build trust and credibility, and generate conversions for your brand at a lower cost — making them valuable assets for your brand.
Because to be honest - my explanation would have been “DUUUH”. Guess that would be the TL:DR version of that.