Google is blocked in some parts of the world, so chance of "being down" is actually non zero if you think of the whole world.

Also, some webpages don’t even run on the internet.

True. Saw this issue first hand on a company internal network.

It's not instead of, it's an additional failure mode.

For years I blocked google-analytics.com because it was on the critical path for far too many pages loading.

The issue isn’t Google being down, it is my ISP’s connection to Google that might be subpar.

They might have a direct peering which is down and unexpected traffic is flowing though transit, you got BGP flaps, you got local CDN outages... and in the eyes of the customer your website is down, not Google CDN.

> The odds of google being down / slow instead of your site are pretty bad.

If my site is down, they already can't access it. Using Google Fonts just adds an additional failure probability, however small it may be.

Google has a reputation of shutting their services down. What if they shut their fonts CDN down or change their URLs without redirects?

This might not be end of the world. In a lot of cases convenience is worth the risks. There is no golden rule that one should never depend on third parties. It is always balancing pros vs cons.

Self hosting introduces extra code, resources and assets that you as a developer must introduce and maintain. This is not free.

Especially if worst thing that happens is a wrong font loaded.

Than a hell of a lot of sites lose their fonts until they update.

To be fair, lots of people being affected hasn't stopped Google in the past.

In the case of Fonts though, it's a good source of user and browser data, so it's not likely to be shut down any time soon.