How so? Apple computers were always somewhat popular in the US, so at least US developers had to have them in mind. It was indeed a very different story in Russia — everyone, literally everyone used Windows, and no one ever considered that other OSes exist.

And for all the application stuff, we've already had a solution, it was called Flash. After all these years, the web still hasn't caught up with it.

And cross-platform GUI apps? These simply better not exist. The proper way is to have a "core" library shared across platforms, and make a native GUI for each platform you support. Many companies are doing this exact thing already with their mobile apps.