Over time we realized that this was not the best way to do it. Browsers have progressed enormously, and there have still been other technologies such as Flash or Silverlight. These technologies gave great creative freedom but they were not very viable in the sense that it comes on top of the browser. Finally, it slowed down the browser since technically we are going to interact directly with a component that runs within the browser. Sometimes there are also large frameworks that do a bit of the same. We have seen a lot of technologies of this kind such as Angular or React which effectively made it possible to save in UX. On the other hand, they have a certain cost in terms of technicality and in terms of performance.
Today, what browser vendors are doing is catching up on all these components. They now natively offer tools, components, faster and more digitally sober and therefore much more ecological means, which are also adapted to mobile needs. This makes it possible to save money and to be more efficient, more reactive.
You should know that historically Flash was undermined by Steve Jobs on the iPhone because it consumed too much battery. We must therefore avoid falling back into this kind of problem and finally return to the web standard which today is very modern.