[ldoughty]

It really depends if you want them connected or not.

In the Hugo example, completely agree. But sometimes it can make sense:

Example.com vs members.example.com vs login.example.com

Example.com can be a static website, while login attempts go to the login domain (which also helps for auth/postback config), and members might be the dynamic content that is viewable once logged in. separates infrastructure in an easy way that has no real impact on SEO