Why is chasing the low considered a trap in Omaha Hi/Lo?
The reason that "chasing the low" is discouraged is because too often, you have a shot at only the low side of the pot.

Let's say you have a low hand draw, and a "high" draw to a straight or flush. Very often, you will make the latter, only to be beaten by a higher straight or flush. At the same time, you may fail to make your low because the card that made the straight or flush is "high."

Ideally, you will have a hand that can go "both ways." Something like K-K-2-3 can make both a high and a low hand, especially of the kings are "double suited" with the 2 and 3. But the best starting hand is A-A-2-3, especially if "double suited." That's because the aces can help make the best possible high hand and the best possible low hand.

If YOU don't have these advantages, someone else may, and you don't want to be playing against that "someone else."