[CM30]

How many sites are on the internet again?

Around a billion.

1% would mean 10 million websites are using each possible feature. Okay, it's not quite that even, and a lot of popular sites (like many news sites) stick to the most basic features, but all these browser features are there for the other various cases. Like aforementioned web apps. Various tech demos. Sites with very specific use cases.

In other words, it's because the internet is massive and varied.