to give you a little example, look at this page. Every section is a _modular page. The good thing is, you're able to rearrange delete or add _modular pages wherever you want to in a template under those the _modular pages listed (In case you're rendering the _modulars in the parent template).
So you're much more flexible with your templates and you doesn't need to create many more static template files if for example the ordering of the sections should be different. The parent template from the example above uses the same template as this even if the content is such different.