developers can only do what most people can experience well. HTML5 uses today are on sites where most people use a primary alternative, and most of these people

developers can only do what most people can experience well. HTML5 uses today are on sites where most people use a primary alternative, and most of these people have a vested interest (Youtube for market share on mobile devices, hearts and minds and also future for licencing technologies etc). It would be an irresponsible developer that let loose with full HTML5 site aimed at "normal" people any time soon if they didnt provide a full standard HTML version as well, which begs a huge budget question. Unless they have no marketing department or CTO to answer to of course.