what's the benefits of using data context in xPages?

Question

I have never used data context in xPages and would like to know the benefits,

If I want to return something in memory I often call function in a SSJS scriptlibrary which I believe is also stored in memory.

so let's say I have a function in ssjs that returns a notesdocument, this function might be called from several places in my xpage. will data context be benefitial in this case in regrards to having a function in a ssjs scriptlibrary.