For many ephemeral workloads, sure, but that comes at the expense of generally worse and less consistent CPU performance.

There are plenty of workloads where I’d love to double the memory and halve the cores compared to what the memory-optimised R instances offer, or where I could further double the cores and halve the RAM from what the compute-optimised C instances can do.

“Serverless” options can provide that to an extent, but it’s no free lunch, especially in situations where performance is a large consideration. I’ve found some use cases where it was better to avoid AWS entirely and opt for dedicated options elsewhere. AWS is remarkably uncompetitive in some use cases.

kv stores also exist because for many generations of tooling it was faster to manage read-mostly data off-heap instead of on, and that becomes more true the more processes you run doing jobs that touch the same data.