Just imagine how boring the web would have been without Flash - at that time. Or did you prefer crashing Java applets? Yes, you had the annoying unskippable intros, but some jaw dropping websites were made with Flash, something you barely see these days. I still remember sites like heavy.com, music bands and movies mini-sites, ...

Take a look at The Web Design Museum, Gallery of Flash Websites: https://www.webdesignmuseum.org/flash-websites/ . Beautiful visuals, terrible SEO.