As someone who recently worked on a spring project for the first time, it's pretty clear what magic we're talking about. I can't look at the code and know what the application does without first learning the meaning of a ton of different annotations and the behaviors connected with them. Annotations and the associated code are complex. Now that I understand what they all do, it's easy to reason about the app, but when I run it my mental model is still:

1. I launch the app

2. Spring does a bunch of stuff I only vaguely understand and can't understand from looking at the code

3. My actual code starts running

On top of that, all the spring stuff makes the memory footprint and startup time awful.