You better hope you dont have any big indexes or your writes will queue and you start getting "database is locked" errors. Good luck queueing writes properly at the application layer without rebuilding a full distributed queue system / network interface / query retry system on top of SQLite.

I really really really wish SQLite or PGLite supported multiple writers, especially if the queries are not even touching the same tables.

SQLite is designed for application databases.

Postgres is designed for client-server.

It's not about "power" (what does that even mean?), it's about totally different design choices that are intended for different purposes. It's an architecture question, not a "power" or "visitors" question.