The only people I've EVER heard talk positively about this is Google & other Flutter Developers that don't seem too concerned about web standards.
Flutter is a cross-paltform app framework. If you have a app on all platforms you (the company) care about the web app would often become just a seconds class citizen which you (the company) only have as some users are hesitant to install apps and some few users have some exotic platform or need access during holidays after their laptop was stolen etc. Anyway from a business POV a second/third class citizen you don't want to spend much money on. So flutter web would be good enough (once it's out of beta, at which point text selection likely will somewhat work).
But if you ever have a web app as first class target you probably would never go for flutter anyway.
My prediction:
- Flutter will long term be come the new default native way to write apps on google phones. Dart will very slowly replace java.
- Flutter will become a serious way to write the UI of apps on Linux, through maybe not as big as Qt/Gtk. But likely a common choice companies which target Linux as 2nd/3rd class citizen.
- Companies mainly targeting Android will use flutter for their iOs, Windows, Linux, Web apps to save cost.
- Google pushes some new Web API's around accessibility to provide a better flutter on web experience. Making it again harder for non chrome browsers, through in this case not intentionally.
I think Flutter could evolve an interesting platform for “line of business” or “rapid application development” projects, similar to Lazarus/Delphi. In that respect, I agree that we could see growth for flutter for low-cost cross-platform projects, and on Linux.
But, after the failures of React Native, none of the mobile developers I talk to have any interest in these non-native, layered-on-top frameworks that need a plugins ecosystem to call into native code or native APIs. Your productivity is basically held hostage by the runtime to an even greater degree than it already is on a mobile OS.
I also don’t thing Google needs any new web APIs to make Flutter accessible. They can position some invisible divs with the right spots with the right WARIA attributes.
React Native has issues from how it bridges all the things from React to native. Flutter shims in the native APIs, but uses it's own components to avoid the bridge issue.
In 2 years, most Android phones are no longer getting updates. Since the flutter app carries along most of its own dependencies, it can continue to provide up-to-date software long after the manufacturers have abandoned users.
Flutter's canvas approach is literally Macromedia Flash all over again. I don't care if it's possible to shim in A11Y into flutter, it's bad for the web and bad for users. They need to rethink how to convert their renderer into DOM elements.