subgrids in examples are referenced via the DOM not XRM - is there a reason for this?

Hi All

I am looking at examples of working with the subgrid of a form in CRM 2013.

Many of the examples out there access a CRM forms subgrid via the DOM rather than the XRM - is there any reason for this (given that CRM does not support referencing form elements via the DOM - with possibly the exception of elements within a HTML web resource)

Can someone provide me with an example of correct way to reference of a CRM form subgrid (2013)  - in Javascript

Thanks

Gordon MacDonald