They're saying that that's the whole point of the realtor. Obviously hiring a crappy realtor that can't find buyers that actually want your house is bad.
Personally I don't believe that an agent finds people that want to buy, one may have more contacts than another, but it is not like the sale goes over or under asked price because an agent is so much better than another, either the initial evaluation (asking price) was underestimated by roughly 10% or the local market allowed a 10% over valuation.
A good agent (as opposed to a bad one) will help (a lot) in a number of other things (bureaucracy, managing and dealing with the details, counsel - if needed - about other professionals such as lawyers and technicians, possibly help in finding a suitable contractor for renovation works, and similar) but they won't be able to raise or lower the price sensibly, the price is mainly due to the market (locally and at that exact moment).
