Explain benefits of representing fragment as custom element

[Guria]

In v4.6.0, Fragments are now implemented using a custom HTML element (<lustre-fragment>) instead of the previous virtual DOM abstraction that didn't introduce wrapper elements.

Given that a key purpose of Fragments is typically to avoid introducing wrapper elements in the DOM tree, I'd like to understand:

1. What were the main benefits driving this architectural change?
2. What were the key considerations in choosing this implementation?
3. Are there any performance implications to consider?

This would be valuable documentation for other developers who might have similar questions about this design decision.