I love to use the example of Wikipedia. As you may know, Wikipedia adds a nofollow to every single external

If I google “Vint Cerf”, the first result is from Wikipedia. The third one is from…google. The first
Then, we still don’t know if adding external links lower the link juice of a web page. If you have 10 internal links on a page, we know that every link leaks the equivalent of 1. Then, if you have 10 external links on the very same page, we don’t know if it divides the link juice sent by internal links by two “0,5” or if the link juice for external links is added to the page.