Breadcrumbs should not be used as a substitute for global navigation. They are a supplementary navigation tool, designed to aid users in understanding their location within a website and to easily navigate back through previously viewed pages.

Global navigation, on the other hand, is the primary way of navigating a website. It usually includes main menu items that link to the major sections of the site and is essential for providing direct access to these sections from anywhere on the site.

While breadcrumbs enhance navigability by showing the path taken, global navigation offers a comprehensive view of what the website has to offer. Therefore, both breadcrumbs and global navigation should coexist in a website's design, each serving its distinct purpose to ensure a smooth and intuitive user experience.