One reason would be that the browser will cache them if they are used in multiple sites, so loading will be much faster on subsequent sites using the same resources. Another might be that such resources load faster off a CDN than your own server.

In practice, this never happens. The value is certainly less than the data you're selling about your users to Google.

What data are you giving to Google (or another CDN) by loading jQuery or a font from them? What does the ToS say? Genuine question.

Edit: here's the ToS: https://developers.google.com/speed/libraries/terms If you believe Google, they're not collecting anything.

Don't be naive.

Value to whom? The site loads faster (so people like it slightly better), it's easier to maintain (less files to serve and keep track of), all for the cost of something the site owners didn't pay for in the first place.

This is often repeated but without any data to back it up its a bit of a myth.

My tests show local resources consistently loading faster than making a link to Google. These are supposed to be cached but thing like fonts are always loaded again. Anyone can repeat this for themselves.

> Anyone can repeat this for themselves.

I tried, they came from the disk cache.