This is not true

We don’t pick features based on their trendiness. If you don’t believe me, see our choice of brunch instead of webpack . Postgres is the default db adapter for new apps simply because in my experience it’s the defacto choice for prod environments, both for my client’s apps, and what I use personally, along with my peers. That said, the Ecto adapter ecosystem has first class support for other adapters, such as mysql, mongoldb, and sqlite that can be used with a single flag to the generator. The issue on the sqlite end is the ecto sqlite adapter has not yet been updated to Ecto 2.0, and the phoenix-core team can’t be responsible to maintain every db adapter that exists. I encourage those in the community who want the best sqlite experience to become contributors on that project so that you can run mix phoenix.new app --database sqlite and be up and running as you wish.

This is not considered a good practice in general, you want every environment to be equal to production. It’s simple engineering 101. Although if it’s your own little project don’t let this stop you.

And lots of projects out there rely on database specific features.

Becase SQLite isn’t trendy enough.
I use it everyday for most of my applications because the deployment & configuration cost is null and the performance impact isn’t visible, compared to PostgreSQL