PHP SDK 2.0 Breadcrumb 'type'

In the documentation on Breadcrumb customization

here

There is the following statement:

Note that the type is not exclusively used to customize the rendering. It’s best not to change the type from the default.

Ummmm.

It would be really helpful if the documentation would go into some more detailed explanation on this point. ie: what else happens when you change the ‘type’?

please expand on this.

thank you!