It works just fine however you need to keep a appropriate headroom to allow the kernel to do its thing with caches as indicated otherwise things get very weird very quickly.
Containers are very helpful in this regard for helping explicitly divide a machine up between processes without allowing any one to get out of hand.
Maybe consider that not everyone has the same use case as you: some people are running larger chunks of computation per node or even stateful applications. Even when they could be killed and are redundant, running a bit slower for a moment until they recover may be preferable to restarting the node (which also takes time).
Do you mean a cluster of many computers that are collectively seen by the OS as a single machine with petabytes of ram? I can I do that too?
The cluster had thousands of individual machines, each performing their own discrete tasks with aggregate ram across the cluster in the petabytes.
There was no swap on any of those machines.