When you install a theme from the HubSpot Marketplace, such as the Generator theme, the assets are set to read-only. This means you cannot directly modify the theme files.

The Generator theme provides a drag-and-drop interface, allowing you to build your site without ever touching the code. However, if you ever need to modify the code one day, it's nice to have the option available.

Creating a child theme gives you this flexibility. It's best to build your pages on the child theme from the start rather than having to switch them over to a child theme later.