So that's the new default for Rails? Seems like a new way for people to shot themselves in foot, for those who are used to the usual postgres + separate services setup. Especially that it's advertised as simpler and therefore is tempting to try out without considering such edge cases. I mean, it's the usual route (from my experience) for successful Rails apps to scale horizontally

What's new is that it's now being recommended for use in production, not just development. It's also now what they want you to use for caching, artifact storage and just about everything else that use to use "Technology X".

I can see the reasoning behind it. Simplicity. But I'm waiting for the horror stories like this one to die down before making a final judgement. It just doesn't _feel_ right to me after doing it differently for 20+ years.

Sqlite has always been the default database for Rails, even though it probably hasn't been the most common deployment choice.

Kind of but not really. Rails has defaulted to creating a project with an SQLite database in development for awhile now. But the expectation has always been you move to what you need.

SQLite has simply become "good enough" for production. So now you can take that dev default and simply deploy it for apps of a certain size and category if you want.