The Knowleses might have been waiting for a dedicated Knowles to dig in dark corners.
But for the aristos, you only have to find one gateway. For instance, if you're descended from William Knollys, 1st Earl of Banbury, his grandmother was Mary Boleyn, the Queen's sister, and she had mountains of ancestry including about 14 Magna Carta barons etc.
Your gateway doesn't have to be a Knollys. It's always the mothers who bring in the bloodlines.
You don't have to research this stuff very hard. You can find it easily on respectable websites.
It's not like it's specific to the Knowles family. Mary Boleyn has zillions of descendants and cousins. Her ancestry is very well known. It's general knowledge in medieval genealogy.
On the other hand, you'll find a lot of solid brick walls demolished if you go looking on less respectable websites, and usually replaced by descents from Rollo. Or Thor if you keep going. Sadly people do collect that stuff. They don't seem to get why Geni knows all about the Duke's son and heir that Complete Peerage doesn't seem to have noticed.
That's just an example. Your friend might be using a different gateway. But the situation will be similar.
This aristo stuff is all on WikiTree already, both good and bad. Needs a lot of work, but lack of information isn't the bottleneck.
(Anjous are to be expected if they're called Geoffrey, Foulques or Ermengarde)