You really don't need to be anywhere close to mega-scale to benefit from SSH certificates and integrated authentication flows, though. Even at the scale of "only" 10 people with SSH access, the whole system can be massively simplified and made more secure by integrating centralized logins, and SSH certificates are rather perfect for this.
I implemented my own SSH certificate authority myself more or less, and while it's overkill for my own homelab-level stuff, I absolutely would never use anything else once I have more than like, 5 people logging into some set of machines. The benefits of centralized SSH access control that you can freely integrate (and pretty easily too, thanks to OpenSSH!) with your existing identity provider is really nice.
I implemented my own SSH certificate authority myself more or less, and while it's overkill for my own homelab-level stuff, I absolutely would never use anything else once I have more than like, 5 people logging into some set of machines. The benefits of centralized SSH access control that you can freely integrate (and pretty easily too, thanks to OpenSSH!) with your existing identity provider is really nice.