Greetings Everyone

So, recently I have been building a world environment and I've made it a point to keep things at a low poly count as I don't want to have a lot of high poly models in my scenes and as I've built I've been exploring Maya's tools and am curious... why would you ever use the (Smooth mesh preview to Polygon) tool? I mean, it adds so many polygons to a model and usually you are told to keep your poly counts down. So yeah, I am curious as to what it's mainly used for.

Thanks & Best Regards
~Chad~