In the general case, almost all websites and web apps don't need offline storage at all.
But the ones that do often need it for very business-enterprise reasons, and here Apple is taking a bit of a risk. I've watched companies hang onto old versions of Flash well past the sell-by date because for quite some time, it was the most practical platform to build a cross-platform videoconferencing client in. And once it's built, the opportunity cost to throw it away and switch to [OTHER_TECHNOLOGY_X] matters.
In the general case, almost all websites and web apps don't need offline storage at all.
But the ones that do often need it for very business-enterprise reasons, and here Apple is taking a bit of a risk. I've watched companies hang onto old versions of Flash well past the sell-by date because for quite some time, it was the most practical platform to build a cross-platform videoconferencing client in. And once it's built, the opportunity cost to throw it away and switch to [OTHER_TECHNOLOGY_X] matters.