Those who've argued that you can't logically give up cue weight at the expense of balance are right, but a light cue that's well-balanced may play very well.
Yes, it's true that for any given velocity of hit, the heavier cue will give you more action. Perhaps of greater import, though, is that for the same amount of energy expended in hitting the cue ball, this may or may not be the case, and it may vary from player to player basd on physical attributes. It's a very tricky tradeoff, but long-time experience of all who've ever played pool explains why most believe that 19 oz and 57 inches is about right for a cue.
Add or subtract an ounce or two or an inch or two to meet your own personal preferences and physical attributes, but I think it would difficult to argue that going much lighter than 19 oz gives you any important advantages.