Safari on a 12.9” iPad is like having an ergonomic MacBook browser. It’s powerful enough to render almost everything the web has (save for chrome specific experiments).

But as mentioned above the killer application isn’t software, it’s the form factor. While I have a decent TV, most of the video content I watch is on my iPad. It’s just more convenient.

To add one more, iOS is powerful but simple enough that I’ve recommended an iPad to most older people I know. They can do almost everything they need on it, and neither of us have to worry about it getting into a bad state like a desktop PC can.

And for most of them, the main thing they use on it is the browser.

It isn't just these applications providing all too common functionality, it is the application centric iPadOS that makes them more than the sum of their parts, also. Apple's implementation of iPadOS and their tablet implementations of these common applications cause each to rise to the level of killer app, and, definitely, beyond all doubt, massively drive sales of the hardware just to use those particular yet common apps in Apple's implementations of them on a tablet. There's no great reason Android on third-party tablet, or whatever is running on Amazon's tablets, can't achieve the same, but they simply haven't. Android more or less sucks. Apple sucks, but with iPadOS + tablet app implementations, much much less.