Avoiding DDoSability of your app (removing bottlenecks, scaling up replicas, implementing rate-limiting, etc). There are probably some rare cases where captcha

Avoiding DDoSability of your app (removing bottlenecks, scaling up replicas, implementing rate-limiting, etc). There are probably some rare cases where captcha is useful, though. For example some account creations where you wish to have more human accounts created, especially if you need to later manually approve them by humans (verifying documents, etc) and don't want to deal with thousands of cat photos instead of passport scans.