I am the author of the Blog. I wanted to share the journey as part of analysis. Blog is not on precedence between || and + but primarily highlight fact that implicit casting cause it to change in Oracle.
Ideally precedence is same in both engines.
Sorry for being dismissive. I've written a post [1] that highlights the core discrepancy between the two dialects. I like criticizing SQL and having a documented case like this is nice.
