That's an interesting test for provincialism. Is it just the UK one must know popular comedians for or are other countries part of the metric? Does this apply only to Americans? For instance, is someone in the UK displaying provincialism if they do not know Canada's most popular comedians?
Sally is Don's firstborn. Don's childhood fucked him up good in regards to women and having healthy relationships with them. Sally is the ultimate expression of Don's dysfunction and she's been designed to show this.