Reading through some (possibly outdated) Quick Start documentation for DXA, I came across this example of putting the site URL in the Site Identifier field in the publication metadata.
In the product documentation, Site Identifier is covered in Configuring the web application for multilingual websites and it seems the only requirement is to use the same identifier for all publications that form part of your multilingual site.
Why would you put the URL there? Is there a real use-case in which this would make more sense than a simple string, or is this just a cargo-cult thing that should be avoided?