Apple was actually one of the first companies to ostracize the troublesome Flash software, which was riddled with vulnerabilities and security flaws. The company refused to support Flash on iOS back all the way back in 2007, and since then others have followed suit, including Google, Facebook, Microsoft and Mozilla. In 2017, Adobe itself announced plans to end Flash support and development in 2020.
The omission of support for Flash in Safari is unlikely to really impact on users, however, as up to this point the plugin had to be wilfully installed, and even then you'd have to really want to use it, since Safari didn't support any other plugins on Mac. Doing away with any and all support, however, signifies Apple's intentions to wash its hands of Flash altogether. Come the end of the year, when Adobe eventually pulls the plug, the once ubiquitous technology will be gone forever.