But I agree in an extremely hypothetical way that the technology choice is unimportant, assuming you can make the same competitive product with a number of technologies. In this case though, especially back in 2005, you simply can't argue that they could have made that product with anything else (apart from desktop software, which is a totally different product space). They were clearly aware of their technology choices, were keeping tracking of the latest and greatest, and chose the only one that was technically feasible for the product they wanted to create.
That said, I agree that flash has been an enabler for many advances on the web. Unfortunately, the flash plugins just seem to be bogged down more and more, and don't seem to evolve very effectively.