It's more Oracle software as SaaS, some basic IaaS (more like a hosting provider than a cloud) and hosted Oracle databases (which are just Oracle running Exadata for you).
So it's big companies struggling to get off old Oracle (and acquisitions like PeopleSoft) stuff and it's gross.
I don't know of anyone using it as "their cloud", but more of another thing to mix in with AWS/Azure/GCP to get rid of on-prem or colo facilities. It's more like IBM Cloud: A way to hang on to customers, sell services (human services like consulting and support), and keep milking those old products for big companies.
A stand-alone Oracle server isn't a reliable solution because patching = outage. So Oracle providing managed Exadata is a win for some (again, usually big) businesses.
Oracle got a lot of companies hooked on proprietary DB features and rewriting can be painful or require spinning up a dev team for something in "maintenance mode". Even Amazon just fully got off Oracle a couple years go IIRC.
I know one successful PaaS which has stayed, which to me says a lot about the quality of IBM Cloud
So basically any business that makes or sells anything that Amazon may possibly make or sell in the future doesn't want to touch AWS.
Do you imagine the fallout if it came out ( and how would in not, thousands of people would have passed through, one disgruntled employee is enough) ? AWS would lose most customers within a few years, Amazon.com as well ( disgusted buyers and sellers), there'd be lawsuit everywhere. I really don't think anyone in Amazon is stupid enough to risk a trillion dollar business for some potential competitive advantage on whatever sold on Amazon.com
What makes you think it would be different with AWS?
[1] https://www.wsj.com/articles/amazon-scooped-up-data-from-its...
https://www.lastweekinaws.com/blog/why-zoom-chose-oracle-clo...
Working flawlessly with ssh, out of the box. It is FAR simpler to manage than AWS in my opinion.
There is "no catch".
Order of magnitude cheaper and way more predictable costs than other cloud providers.
Companies also use Oracle Cloud PaaS to build custom enterprise applications