hey @eeejay do you remember why you added this in #23013 ? From our point of view it's useless (because we programmatically give the focus if the user click in a blank space in the panel) but maybe you had a reason for a11y?

The consequence of this property is that a recipient being edited takes the whole available space. Without this property it takes only the space its content needs.

From an accessibility perspective, that empty space that a user clicks needs to have an appropriate role. I had the entry grow and take up all that space, so that a blind user will have an easier time finding it. In other words, the recipient list looks like this in accessibility:
[recipient button], [recipient button], [entry ]