JSTL vs JSP Scriptlets

Question

I want someone to explain some points in BlausC\'s amazing answer in this question.

He said that scriptlets had some disadvantages, which are:

1. Reusa

Answer 1

I can't speak for BalusC but in general I believe he was getting at the idea that these kinds of things should be accomplished by your ordinary Java code (in the Controller and Model layers if you're into the whole MVC thing).

1. You can't literally reuse JSP tags at an individual level, but you can reuse the classes they call into.

2. JSTL can't be abstract, but ordinary Java code (which you can perhaps invoke from JSTL) can be.

3. Again, you can't make objects usefully in jstl, but you can in all the classes that are called.

4. JSTL by itself is not unit-testable. But the classes and methods you call through it are.