Are you sure you know what DI is? It just means you pass an object's dependencies to it, instead of it constructing them itself. You don't need a framework to do DI.

I don't believe you. Are you mistaking DI for meaning a full blown IoC framework? DI is merely the abstract computer science concept. In FP land we call it partial application or P/A. But it is essentially the same thing. I honestly cannot fathom how a large project would look without DI. It must be hideous with massive amounts of coupling all over the place i.e. not something to be proud of. Refactoring must be very hard.

I would have to take a few guesses to know what an AbstractFactory is. That is a "J2EE Javaism" and always has been. So you aren't alone there ;)

I'm pretty sure it's impossible to write a non-trivial program without ever using DI, even if just by accident.

Agreed. If you've not used DI after 15 years as a "professional" developer, and you are also happy to "boast" about this fact on the Internet, then it means you are very likely an utter shit developer.