That is very understandable.
Yes, of course, a literary agent is working on behalf of the publisher and would require exclusivity for a literary project.
For a manuscript, I am much more likely to work with a literary agent to get my book picked up by a publisher.
It can imagine that it would increase the likely hood of being published by that same publisher or being published by other publishers for similar projects.
In your experience, are you published by the same publisher repeatedly or have you worked with multiple publishers?