Can you gain the performance benefits of partition elimination without changing SQL module or table definitions?
Possibly, but in my experience you don't partition data for performance reasons. Yes, partition elimination can reduce the IO that some queries consume but there are complications that partitioning will introduce, see here for my favourite. 

What partitioning does help with is maintenance. You can rebuild indexes, and stats (on SQL Server 2014+) at the partition level. This can be a huge win when you struggle to keep maintenance operations inside your maintenance window.

Partitioning is also great when it comes to loading and archiving data. The SWITCH statement is your friend here.

Lastly partitioning can also be used to optimise columnstore indexes by introducing a level of ordering to the data. This helps with dictionary pressure. Each partition acts as it's own columnstore index which means you get more global dictionaries as well as delta stores and delta bitmaps. Niko's blog has much much more info here