One of the subsidiary roles of conferences is recruitment. NIPS is optimally placed in time for this because it falls right before the major recruitment season.
I personally found job hunting embarrassing, and was relatively inept at it. I expect this is true of many people, because it is not something done often.
The basic rule is: make the plausible hirers aware of your interest. Any corporate sponsor is a “plausible”, regardless of whether or not there is a booth. CRA and the acm job center are other reasonable sources.
There are substantial differences between the different possibilities. Putting some effort into understanding the distinctions is a good idea, although you should always remember where the other person is coming from.