Back in the day I used to be among top users on that site - they even sent me a T-shirt at some time. Left several years ago, as the site became toxic.
I'm not mentioning this "top user" thing on my resume anymore, because not relevant.
The site is still an excellent source of information about all things that were cool ten years ago, such as Java, Spring, SQL, Python.
This might be excellent: fully implemented MERGE in other RDBMS seemed to be highly unreliable. Given Postgres' focus on quality, not on number of features, not implementing MERGE fully might be a great choice.
Just imagine how many permutations we'd need to unit test the implementation of full MERGE. Sounds scary. Better develop a frequently used subset, the UPSERT, and stop at that.
I'm not mentioning this "top user" thing on my resume anymore, because not relevant.
The site is still an excellent source of information about all things that were cool ten years ago, such as Java, Spring, SQL, Python.