Many of Oracle's locked in customers come from startups that Oracle purchased.

Oracle goes around looking at the lock-in potential and acquires based on that, then they ride that startup product's reputation for as long as possible until they just leave it to rot. They also try to bundle in existing Oracle products (e.g. Oracle DB) almost giving it away to get your foot in the door then dumping on you.

Unfortunately a lot of companies find themselves in a business relationship with Oracle, even after never having purchase an Oracle branded product.