> Which raises the question: why is it such a successful company commercially?

Tons of mediocre enterprise software is built on Oracle DB.

Why enterprises are vendor locked-in? There are very few large enterprise players in every industry that implement all kind of ISO, standards, got an army of business analysts to generate million of requirement pages. Any new player must fight against that artificially overblown legacy systems, design and prove migration process is possible etc.

Here are just a bunch of industries my family/friends worked in and had first hand experience with these legacy systems - Airline (PSS), Banking, Healthcare, Hotel, Telecom.