Otherwise intelligent devs assume they can do a better job without all the "complication" and "bloat", but then just end up with homegrown unmaintainable crap that does half of what the frameworks offer for significantly more effort.
It's either stupidity or arrogance.
At least with Spring, you only have to learn it once.
I don't see how you deduct the conclusion of reinventing wheels is the only solution of overcomplex and far from ideal frameworks. But you can categorise this deduction also.
The trouble now it is that Spring Boot allows getting things up and running without having to know anything about what is underneath.
That is great, until you have to change the way it behaves.
Developers should not be writing code. Period.
Stupidity and arrogance is ruling everywhere.
You can use as much of Spring or as little as you want. Don't want Hibernate? Use JDBC template.
I have noticed that people who don't use a framework, just end up inventing their own bespoke framework, which unlike Spring, is not documented and has no help available online.