What is the use of "context" argument in the RegisterMarkdownPostProcessor?

I see that there is an argument named “context” when we use RegisterMarkdownPostProcessor. I wish to know what is it used for or how can i use it? any idea?
Can i use it to retrieve the block source later in the function calls without passing the source or element in all the functions?

this.registerMarkdownPostProcessor((element, context) => {
            console.log("callback called");

It gives you additional information, see: MarkdownPostProcessorContext - Developer Documentation

ctx.addChild is usually accessed to provide a lifecycle management for child components, AFAIK