The pattern evolved from early Java’s lack of reflection. In order to give tools the ability to set/get data, we got the JavaBean. The culture internalized the pattern, and we’ve been mindlessly doing it ever since.
I only quibble on the "mindlessly" part. I will never add a get/set in a class if it isn't needed. But invariably, in a Java project, some library somewhere insists that I have them. So eventually I find I've reluctantly added them.
Sometimes you can get away with leaving them private, sometimes not. It's a pain in the neck and like many things in Java, it should have been sorted out years ago.
I'll grant that you're mindful ;-)
One thing I've noticed more and more over the years is this tendency for folks to do things that under analysis make no sense and have no benefit.
Even worse, I have a bad feeling that 20 years ago I was one of those people...
It definitely is the case that reflection in the JDK would be a very slow and ungainly way to do data access so I can see the 'bean' convention being a way around that.