If you are tech lead or manager, these frameworks are really great value because they "give" (or more like let developer find) guidance on a lot of aspects of the application.
If you created your own perfect framework, you would be responsible for providing a huge amount of that kind of guidance, but if you are using Spring your every developer can just google the answer to most (or even almost all) of the problems.
And the second point is, again, if you are tech lead or manager, these frameworks are great help preventing your "highly intelligent" developers from making a mistake and developing their own framework. I put quotes intentionally, because some developers just think themselves to be very good developers but dismiss the risks and costs of developing software that is not core part of the project (aka NIH).
With Spring regulating most aspects of the application any damage from those kinds of actions is also limited.
It's a bit of a struggle because an experienced dev will hate the framework, as they know better, but then as less experienced dev work on the code base it'll degenerate in a way the framework would have survived longer due to availability of documentation and Stackoverflow Q/A.