Yes there's a lot that a company could do fake a good OOP architecture which compiles down to standards soup, but such solutions tend to result in tons of extra generated crap. Dart compiles to JS... with a a simple "Hello World" app coming out as 17,000 lines of code!

Plus not having the structure as part of the standard will make iterative development a nightmare. Instead of being reliant on a proprietary runtime (like Flash Player) we are reliant on proprietary compilers and libraries. How is that better?