The JOIN mode has been in preview for over a year and is slated for GA release within a few months. Which has been on their roadmap.
The removal of the rust service is available in preview for Postgres as of 6.7.[1]
Rewriting significant parts of a complex codebase used by millions is hard, and pushing it to defaults requires prolonged testing periods when the worst case is "major data corruption".
[1]: https://www.prisma.io/blog/try-the-new-rust-free-version-of-...
It is hard.
Harder than just doing joins.
Honestly, everything you say makes me want to stay far from prisma _more_.
All this complexity, additional abstractions and indirections, with all the bugs gootguns and gotchas that come with it... when I could just type "JOIN" instead.
They've had flags and work arounds for ages. Not sure what point you are trying to make? But like you said I've never used it, only heard of it lol.