That is likely because Internet Explorer 11.0 does not fully support HTML 5 so Flash is a fallback on that particular site for people still using Internet Exploder. Microsoft has dropped Internet Explorer and their current browser is Edge which is fully compliant with the HTML 5 standard and drops support for ActiveX and other Microsoft proprietary technologies.

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein