Exactly, to not make a feed-to-sleep association, but also because it makes it easier to understand why they're crying. If the baby ate and 30 mins. later starts fussing you know it's time to sleep, you don't have to guess if it's hunger because you just did that.
If the baby eats and then sleeps, hunger and tiredness go together and it's harder for the baby and you to understand what's going on. By keeping things separate, baby can maintain the different cries and it's easier for you to learn to distinguish them. Also, by separating the two, the baby learns to stay awake for the feed which makes feeding easier for both, and ensures a full feed (especially hard to see when breast-feeding).
It does makes life a lot easier!