If economics don't line up then you have to pull the plug and set them adrift, which is much easier and more secure with a fat client that runs without a server than say, a complex cloud system.
This sounds like the set up for a "No? Me neither." punchline. Certainly one of the features of Flash is that it gave you fairly good consistency across computers, but honestly my perception of Flash wasn't that it was going to solve some grand web problem, but more "oooh look, shiny rollover buttons!" and "ooh look, super obnoxious advertisement that forces people to pay attention to it!"
That's the interactivity aspect. At the time, it was the bees knees of UI capabilities.