Those are exactly the problems that Adobe was supposed to solve. And it’s not like it was mission impossible. I’d say everything we have today still sucks compared to Flash. Building a website with the level of interactivity, micro interactions and animations using today’s technology is super complicated and almost impossible for a single person.
> [Web integration, accessibility, and responsive design] are exactly the problems that Adobe was supposed to solve. And it’s not like it was mission impossible.
"Solve" is weird in this context, but Adobe did make good progress in each of these areas, first by supporting some of them in Flash Player, and ultimately by abandoning the proprietary runtime.
> Building a website with the level of interactivity, micro interactions and animations using today’s technology is super complicated and almost impossible for a single person.
Flash was never for this (other than in a "if all you've got is a hammer, everything looks like a nail" sense), but if that's your benchmark then you can still do that with Adobe Animate.
Some people only had the skill to wield a GUI builder/animation timeline-type hammer, and deploying to the web was the only nail that mattered. For them to have access and distribution to that audience was killer, and we’re all worse off for the lack.