Explanation
OCI leverages advanced encryption that leads to fast performance, OCI does not over subscribe CPU, but only memory, and OCI hypervisor provides industry leadingperformance are WRONG.
However, OCI does back claims with SLAs and offers predictable pricing for all services.

Fault domains can protect your application against unexpected hardware failures or outages caused by maintenance on the underlying computer hardware. Additionally, you can launch instances of all shapes within a fault domain. Oracle Cloud Infrastructure is typically designed with three availability domains per region, and each availability domain has three fault domains. When carrying out maintenance on the underlying computer hardware, Oracle Cloud Infrastructure ensures that only a single fault domain is impacted at one time to guarantee availability of your instances in the remaining fault domains.

Getting started is easy. When you create a new compute instance using the API, CLI or Console, you can specify the fault domain in which to place the instance. If you don't specify a fault domain, the instance will be distributed automatically in one of the three fault domains within that availability domain. Oracle Cloud Infrastructure makes a best-effort anti-affinity placement while optimizing for available capacity in the Availability Domain.
Reference:
https://blogs.oracle.com/cloud-infrastructure/introducing-fault-domains-for-virtual-machine-and-bare- metal-instances

Explanation
Changing the Shape of an Instance (Horizontal Scaling)
You can change the shape of a virtual machine (VM) instance without having to rebuild your instances or redeploy your applications. This lets you scale up your Compute resources for increased performance, or scale down to reduce cost.
Autoscaling (vertical scaling)
Autoscaling lets youautomatically adjust the number of Compute instances in an instance pool based on performance metrics such as CPU utilization. This helps you provide consistent performance for your end users during periods of high demand, and helps you reduce your costs during periods of low demand.
As load increases, instances are automatically provisioned: the instance pool scales out. As load decreases, instances are automatically removed: the instance pool scales in.

https://docs.cloud.oracle.com/en-us/iaas/Content/Compute/Tasks/resizinginstances.htm

Availability domains are isolated from each other, fault tolerant, and very unlikely to fail simultaneously or be impacted by the failure of another availability domain. When you configure your cloud services, use multiple availability domains to ensure high availability and to protect against resource failure.
Reference: https://docs.cloud.oracle.com/en-us/iaas/Content/GSG/Concepts/concepts.htm