You’re correct that it isn’t as good of an alternative as flossing but you’re meant to do both.
You should floss, preferably with actual floss and not a pick, and then follow that up with water irrigation. You dislodge food and break up the plaque with the floss and flush it out with the water flosser.
Such an amazing series! I love that there are content creators who make documentaries that rival mainstream production companies in terms of quality and their content is practically free.