That's how all frameworks work though. This is not a criticism of Spring Boot. You are criticizing the use of a framework at all.
Some people hate to write the same basic things over and over. That's where a framework excels. Write only the glue/logic you need to make your app work.
The way you have described your experience with Spring Boot seems to imply you did not take the time to learn it at all, and therefore its' unsurprising to us you had a hard time of it.
Not writing the same thing over and over again is a feature of abstraction. A framework is a user-hostile way to abstract because it makes the source code opaque to developers. There's no reason why a library-based approach has to be more repetitive than frameworks.
Right, so you cobble together 48 different libraries, wrangle all of their configurations and stitch them all together yourself.
You do this 18 times because you have 18 different apps with similar requirements but deal with different data/endpoints/whatever.
On your 19th app you decide to standardize how you cobble together all of these libraries so that you don't have to start at ground zero every single time.
CRUD backends have well-understood requirements, in a way, a significant part of the work is done for you. You are there to customize certain parts only.
How else would you architect with this in mind? Given that literally every other framework is quite similar (RoR, PHP's solutions, etc).
There is another niche, the HTTP server libraries, but they are much more low level.
