The part that's not mentioned is that there's no real latency guarantee on these IOPS. If you're running a database that has to do a few data dependent reads (eg. walking a B tree), then these can add up quickly if latency spikes to dozens of milliseconds (eg. this datadog blog post [0]).

[0] https://www.datadoghq.com/blog/aws-ebs-latency-and-iops-the-...