Sharepoint Publishing Page Edit

I ran into a problem today where I was giving a user permissions to edit a publishing page in a Sharepoint 2010 publishing site.

The user has owner rights to the site, but they are getting the standard "Access Denied" error when they try to edit the page. They can make all other changes (including permissions), but cannot edit a publishing page.

Turns out, you must give read rights to the Master Page list if non-site collection administrators want to edit publishing pages.

Dumb. But, that's the fix.

Can anyone help me understand this? Users need read access to the Master Page list in order for the system to use it, right? So then, why do we need to give further read rights for this specific purpose?