You probably experienced it yourself, or at least heard about it. The internet broke for half an hour on July 2nd, 2019. What really happened was Cloudflare, a major CDN (content delivery network) provider, had a global outage. But it effectively broke the internet, because majority of websites either use Cloudflare directly, or depend on a service which uses it.
This shows us how the whole web is getting more and more centralized and if one of the major players has issues, everybody feels it.