Tags are a way for a machine to know which words in an article most accurately represents the content of the post. They are used by many networks and systems (including Passle) to recommend content to users, based on posts they have previously read or written. 

Whilst it's an imperfect system, what it means is that if you don't tag your content, many of the machines will simply not be able to promote you as effectively as if it were. 

So, if you want more reads, shares and feedback, be sure to tag your content.