I'm asked this question all the time.
(Though not usually by our beta-users, as they're all branding & marketing types who use our platform to easily create data-driven personas.)
In my experience, the benefit to creating and using customer personas is that they get everyone on your team on the same page, moving in the same direction, using the same "single source of truth" instead of being all over the place.
In other words, personas provide:
1. Focus
2. Alignment
3. Direction
If you've ever worked with (or for) an organization that's out-of-sync, you understand how big a deal that is.
Here's an example of a persona for a CEO.
