One reason is that a lot of mobile browsers won’t resolve local-only domains or even IP addresses unless you explicitly put https:// in front of it, every time. Instead they treat them as a search and you end up searching for your local domain in a search engine. It’s a pain in the ass and having a public, registered domain gets them to properly resolve even when your local services live on a non-public subdomain.
One reason is that a lot of mobile browsers won’t resolve local-only domains or even IP addresses unless you explicitly put https:// in front of it, every time. Instead they treat them as a search and you end up searching for your local domain in a search engine. It’s a pain in the ass and having a public, registered domain gets them to properly resolve even when your local services live on a non-public subdomain.