What problem does this address?

New users aren't always sure where to add their logo. In our user testing, someone tried to change the logo in the style book, and if a theme doesn't include a logo space by default, they may not be aware they can add one.

What is your proposed solution?

Add a global setting for the site logo, perhaps in Styles as the user anticipated, or maybe someday in a Site Identity area in the Site Editor that includes the logo, title, tagline, icon, contact, social links, etc.