You're using the concept of "sharing" incorrectly. "Sharing" is something consumers do after a content creator publishes something. If the content creator is attempting to make their content go viral by "sharing" it across several platforms, they're failing. Since there are multiple instances of the same content, the consumers can only pick up and "share" each instance a few times, so it stagnates due the fractured nature of the markets. X amount of consumers carry THIS link, this far. X amount of consumers carry THIS link (which is the same content as the previous link), this far. Each instance dies out, just like it would if it was going viral, but a lot faster since there are fewer hands/eyes on each instance.

If there was one instance surrounded by all consumers, then it can spread and pick up momentum. All eyes would be glued to the same instance, some eyes would share, more eyes see, and so on. One instance. That's how the internet has always worked.