Perhaps you're unaware that billions of devices attempting to resolve Facebook's unresolvable domains effectively DDOS-ed the DNS system? It most certainly did slow down big chunks of internet which otherwise had nothing to do with Facebook.
> Some applications may have seen increased load and suffered due to server resourcing constraints, caused by applications like the above failing to fail gracefully, and instead polling more aggressively.
I had Cloudflare's woes in mind when I wrote that.
Based on cloudflare's own blog[0], 1% of queries went unanswered for about 10 mins, and were significantly delayed for a few hours. 5% of queries were delayed for a couple of hours. 95% of queries continued to be resolved as normal.
This is referring explicitly to users of 1.1.1.1, which is likely not the same infrastructure as domains hosted by cloudflare dns.
I had Cloudflare's woes in mind when I wrote that.