LTS was proposed by Mark Reinhold [1] who leads the JDK Project in the OpenJDK community in 2017. There was a lot of discussion [2] that resulted in many vendors supporting and adopting the LTS model.

It's a thriving ecosystem (which is great!) but yes, Oracle does contribute a significant portion [3].

[1] https://mreinhold.org/blog/forward-faster [2] https://mail.openjdk.java.net/pipermail/discuss/2017-Septemb... [3] https://inside.java/2022/03/22/the-arrival-of-java18/