I'm not talking about free usage, I'm talking about people spending serious money on cloud services. Cases I've heard about, Oracle sales were willing to engage in much more aggressive discounting on a large deal than AWS or GCP or Azure were, making going with Oracle pretty much a no-brainer from a cost viewpoint. I've heard similar stories about IBM as well. I suppose the second-tier players feel a need to fight for business that the first-tier players don't.

No idea about their web UI (although it can't possibly be as bad as the UIs of some of their legacy on-premise products) – but serious usage one tends to use the APIs much more than the web UI.