All software products have documentation on how to install the product. Oracle has a large suite of products, their databases, ERPs, etc. For kernel parameters, its just a file, which takes a second https://docs.oracle.com/en/database/oracle/oracle-database/1...
In reality though, all Infra teams, have infrastructure to install OS (and manage the fleet), then post-install customize the OS to which team is requesting, usually done via puppet or ansible to manage the configuration. There will be standardized configuration for application, web, database (just to keep it simple).
I would be shocked if Oracle support (or any other vendor) is given login access to make changes on servers owned by clients. At best, you open a case, you get an incompetent support person who'll send you documentation.
Oracle support does not replace admins. Oracle support gives you access to bug fixes, updates, documentation. I believe you can download most Oracle software for free, but without the docs and updates, its worthless. Other vendors may use the opposite strategy, docs openly available but software downloads are paid/subscriptions.
> Spending $500k/yr on compute+support SLA is cheaper than $200k/yr on compute and hiring 3 admins dedicated to that piece of compute.
In reality though, there will always be admins, then a whole lot DevOps/Cloud Ops/Kubernetes/SRE/etc people added, smooth talking manager/director increasing the spend from what could be done on bare-metal under 20K to a 20 million dollar multi cloud strategy. Why have 3 admins report to you, when you can have an army of 200 people do the same work for 100x more cost? Success stories and promotions all around!