I think automatic scaling is useful to utilize server fully - apps that don't need resources automatically scale down, apps that need resources can auto scale up.
I bet you can do it in some other way but that's built in feature of k8s.
I bet you can do it in some other way but that's built in feature of k8s.
There are no benefits to scaling down in this case. And scaling up won't help handle more load if you've already allocated all resources to running replicas. You need more machines, not more replicas on the existing machine(s).
It all comes down to simple, boring capacity planning and static resource allocation. Fewer moving parts results in fewer failure modes, hence more robust infra and less ops and maintenance work.
You have apps A, B and C (you have N teams and N products) each developed by different teams - that you want to run on that one server, when app A doesn't have much traffic apps B and C can use more of compute. Then having deployment management aligned for all teams/products.