Vault isn't easy to use at any kind of larger scale, though. It works well enough for small deployment infrastructure. Once you get to a certain size, all of HashiCorp's tech starts to show its poor, overengineered design in both performance and stability.
Could you elaborate a bit on what you consider large size? Did you have issues with Vault specifically? In my experience Terraform is the troublesome Hashicorp tool, not Vault.
