I ran my living room laptop with 8GB RAM, Ubuntu 14 & Chrome for a few years with zero swap. I had forgotten to create it & it was never an issue.
The rule of thumb is if you're swapping, add RAM.
I was managing some OpenStack servers and when they started using any swap above a baseline, it was time to reboot them because they would always be slower after that happened. Then they'd be good for another month or 2. Swap was useful as a canary.
I'm not sure if it's better to crash & reboot for low ram or have a bit of swap to allow recovery until you can reboot.
With cloud, you should have multiple VMs and compute nodes. And your apps should be HA so you can reboot nodes w/o affecting your apps. In that case, no swap on the VMs, ever.