I have a strong philosophy too:

If some higher up would tell me something like this I would update my CV and start looking.

Bandit only works with plug for handlers anyways. It doesn‘t have a separate bandit specific handler abstraction.

I‘d still go with ecto, even if you just use it as a means of having a repo to issue sql queries against. But it‘ll be a less harsch to move once you want to use more of the toolkit

NIH-syndrome?

To be honest, this philosophy usually ends up in having to keep more in the head than just using phoenix.

Sure, using “vanilla bandit” will also work, though depending on the scope of the application, you will eventually ending up writing your own abstractions, which any new team member had to learn, making their onboarding more complicated.

While with phoenix, you can just assume, developers know it, or will at least be able to a “blog in 15 minutes” tutorial before having their first day (or even. on their first day) and be able to understand the most important concepts.