Part of the threat model for an Engineering team is that people come and go. They move teams which have different levels of access. They leave the organization, in most cases, on good terms. I want to set up infrastructure where I don't need to remember that your SSH pubkey is baked into production configuration after you leave the company.

There are several options for setting up per-connection keys that are dispensed to users through the company SSO. That setup means you don't need to maintain separate infrastructure for (de-)provisioning SSH keys.