Linux wasn't a 2nd class citizen to the people who used Linux. Thus some people see Flash as an anomaly that needs to be replaced by web standards that are so good that Flash becomes unnecessary. That way all platforms get rich client capabilities including ones that weren't even invented yet (Raspberry Pi, Fuchsia, others).

You can only see Flash as a good thing if you're using one of the platforms that are more equal than others. (And I include Java Applets, ActiveX, and Silverlight along with Flash.)