I’m curious as to how you know this if it is, in fact, true.
Oh. That's because:
Star Wars is based on a Kurosawa movie and it heavily influenced pretty much all big blockbuster movies today. Also, modern westerners have been heavily influenced by Kurosawa's samurai movies and the whole spaghetti western genre was developed out of Kurosawa's Yojimbo. Besides, Ikiru is Spielberg's favorite movie, hence Spielberg was heavily influenced by Kurosawa, while Scorsese was also heavily influenced by Kurosawa and he even acted in one of Kurosawa's later movies. Also, the kings of European film, Bergman and Tarkovsky were big fans of Kurosawa's movies even his samurai action movies. While the king of animation, Miyazaki, claims that Kurosawa is his greatest influence in terms of direction. Miyazaki in turn has had enormous influence on modern Japanese, Chinese and Western animation. Hence, Kurosawa directly exerted enormous influence over the films made in US, Europe, Japan and China.
Also, when one does speak of great film makers, Kurosawa is always included. He is universally admired both by Japanese critics and Western critics and critics everywhere else. For instance, Iranian film critics when they made a list of top 10 best non-Iranian movies ever they obviously included a Kurosawa movie.Kurosawa was even named the Asian of the century in cultural fields:
https://en.wikipedia.org/wiki/Asian_of_the_Century
Finally, Kurosawa is a director that achieved simultaneously popular and critical success, something that's extremely rare in any field and specially in film. His influence was enormous not only in film but many other artistic fields. For instance, many early manga artists were heavily influenced by Kurosawa's visual language. He was essentially a master in using images to tell stories and convey symbolic meaning and remains the gold standard by which conventional film is judged.