Flash and Silverlight follow what I said. They were ubiquitous until the costs, being a bloated platform that couldn't be ported to smartphones, caused the industry to shift to an open model.
And messaging is a very old use of the Internet. IRC was created in 1988; Discord shouldn't be a thing based on what you've said.
That assumes the "mirrored" communities are mirrors of each other. The instance that the community is hosted in really affects the community.