Yes and no. In outage periods, S3 access is often degraded because throttling is greatly increased, leading to 503s. Meaning if you have that cache layer on top of it, you dodge the issue.

Where it doesn't help is if Cloudflare itself is having issues (all it does is move the weak link one layer up in this case). But that is easy enough to disable (assuming the cloudflare API or dashboard is up).