I've never heard of that method. I don't think it's very common, nor do I think it's sensible. A more common and better variant is to not count both distribution and high card points for a suit unless the honor is an A (for a singleton or doubleton) or a K (for a doubleton). Thus, QJ doubleton would be worth 3 points but not 4.
The rationale for the rule that was suggested is no doubt that your honors are unprotected -- if the opponents play AK, your honors drop. The reason this is wrong is that if you partner has at least one of the A, the K, or the 10 (which happens more than 2/3 of the time), your QJ doubleton becomes valuable again. Even if partner is missing all those cards, you still have a decent chance of winning a trick with one of your honors provided you don't end up dummy, because the opponents will have to guess how to play the suit. Another way to see that it is wrong to value the holding at 1 point is that QJ doubleton is clearly much better than xx doubleton, which would also be worth 1 point.
The more advanced answer is that the value of this holding depends strongly on what partner has and to a lesser extent on the contract. Therefore, you should re-evaluate your hand during the bidding as you get more information about your partner's hand and the opponent's hands. For instance, if partner seems to be reasonably strong in this suit, your QJ doubleton is probably valuable -- it could be worth 2 or even more tricks. On the other hand, if your LHO seems to have all the cards in the suit, your QJ doubleton may only be valuable for the fact that it is a doubleton.