Comment by psidebot

Disk hardware may be faster relative to RAM, but if you're using typical serverless PaaS offerings to run a hosted application at modest operational scale, it's a heck of a lot cheaper to get a node with "normal" RAM and CPU, than it is to get decent IOPS. If you're a big iron company with big iron problems, you may need to think in different scaling terms, but for the SaaS hoi polloi the economics of hosting have somewhat preserved traditional notions of performance.