Unless they spend most of their code fighting the framework to accomplish their actual task. Which happens rather often.
Not to mention that learning a new framework is not fundamentally different from learning some person's approach to doing things. Whether or not it's easy depends on the quality of code and documentation. Given equal size of the code that does the job, reasonably written framework-free code is probably going to be easier to understand, because it doesn't have external dependencies.
I never understood why after years of dealing with dozens of competing and rather poorly constructed web frameworks in Java, PHP and now JavaScript people still believe that those things have some kind of inherent value. Remember Struts, anyone? PHP Nuke? WebForms? Would you rather maintain something that used either of those over something that was written in vanilla Java/PHP/C#?