I'd like to see how a web app of similar complexity would run on the same hardware. For all that people remember Flash being slow, remember the era of hardware it was running on.
By the time the iPhone was introduced, PC hardware was well into the GHz era with multiple GBs of RAM. The phone was much more constrained and didn’t have disk swapping.
In that case why were the minimum requirements for Flash for Android when it did come out in 2010 and 1GB of RAM and a 1Ghz processor and then it barely ran, ate up battery life, and was soon discontinued?
The first iPhone that came out with those spec’s was in 2011.
So doesn’t that kind of tell you the answer to how Adobe was full of it when they complained that they could have ported Flash to the 1st gen iPhone if it weren’t for Apple blocking them? The fact that they couldn’t get it working well on phone hardware four years newer, over twice as fast, with 4 times as much memory with larger batteries?
Cross platform frameworks like the initial poster alluded to always suck compared to native purpose built frameworks.
We see that today with Electron - a battery killing, memory inefficient, platform.
Flash on the Wii, as I recall, worked well mostly for flash games that were designed with the Wii in mind, and for very simple interstitials. Anything more complex did not work well.
I think Adobe could have done something similar on the iPhone. I don't know that it would have been what people wanted, and I think it would have exposed some of the iPhone's hardware limitations to users.
Mostly though, I think Flash was a heck of a lot better than what we have today with overly-complicated webapps and Electron, as you referenced. That's the point I was trying to make—we've ended up with something even less efficient than Flash ever was!