For certain apps, bandwidth cost is stupid expensive on AWS.
For example I've been following the development of an online manga reading site (mangadex.org) that is now pushing over 1PB/month of images. If they had built it on aws, even at the lowest rate of $0.02/GB with cloudfront/S3, it would be $20,000 per month. But they ended up paying nothing by using cloudflare who gave them unmetered bandwidth.
(well, until they got throttled earlier this year but they got out of that by upgrading to a measly $200/month plan)
For example I've been following the development of an online manga reading site (mangadex.org) that is now pushing over 1PB/month of images. If they had built it on aws, even at the lowest rate of $0.02/GB with cloudfront/S3, it would be $20,000 per month. But they ended up paying nothing by using cloudflare who gave them unmetered bandwidth.
(well, until they got throttled earlier this year but they got out of that by upgrading to a measly $200/month plan)