Just my emotional reaction: I am amateurishly selfhosting for more than ten years with only basic linux knowledge. This training is probably more focused on pros and general web development than self hosting. In my imaginary perfect world self hosting would be a common skillset taught in a secondary school.
One other reason I imagine is to establish a single family name, especially with children in mind. I’m not sure it actually works better than a double damily name, but it probably seems so to some.