I have to question what some people here think a talent agency does.
They do not influence the content or the topics of the streamer or anything. As a viewer the most you'll actually see of the agency is the business email.
The agent represents the talent in contract negotiations and is the first point of contact for potential sponsors, at which point they will negotiate the best rate before presenting the sponsorship or contract to the talent who will ultimately still decide whether to take it or not.
Producers will approach the agent, not the actor, for auditions. Teams will approach the agent, not the player, for signing them. A bullshit marketing summit will approach the agent, not the speaker, for speaking engagements. An organizer will approach the agent, not the singer/band, for festival appearances. That's all it is.
Ryan Reynolds does not have to do a show with Serena Williams, Hillary Clinton and Hideo Kojima just because they're all part of the same agency.