Title said “no overengineering” so I doubt it.

I would argue that Oban isn't overengineered.

If so should we also consider PostgreSQL overengineered?

It's a shame OP decided to use Elixir as base, many ecosystems don't have mature task queues (e.g. for Rust I had to roll my own: simple_queue) so the space IMO would be more welcoming.

On OTP doubt anything can even make a dent in Oban user base.

Satisfied former Oban user here. Oban is engineered. Your use-case may be petty, though, like your comment.