Currently, the identity service requires a port to be specified for all hosts that aren't web.comm.app.
However, when a port is specified that happens to be the default port for a given scheme (eg. 443 for https or 80 for http), the url crate ignores the port, and url.port().is_none() will return true.
As a result, there's no valid way to specify a host with a default port. This led to ENG-9865.
My assessment here is that requiring a port isn't super necessary... if it's skipped, then it's reasonable for us to just use the default port for the given scheme.