If you can run 1 server instead of 3 though... that means no ansible, no kubernetes, no wild deployment strategies, 1/3 the likelihood of hardware failure, etc
This isn't true, at all. We are not "high availability" by any means but running on one server has significant risks, _especially_ if you don't use some form of automated provisioning. A destructive app logic bug is far more likely than a hardware failure, and in both cases the impact on your service is significant if you have one instance, but likely manageable if you have more than one.
