The publications can not be faulted for giving youth advice about avoiding irresponsible sexual situations, drugs, and other perils that come with immaturity. They give mostly standard issue advice about these things. But then they really drop their credibility when they write about masturbation. They show that at their core, the writers and editors, and ultimately the governing body members are evil manipulative cunning people.
They outright state that masturbation is not mentioned in scripture. They are correct. In fact, the best that centuries of church scholars have come up with to criticize the matter was in Genesis when Onan was struck dead for spilling his seed on the ground and not impregnating his dead brother's wife. Even if he masturbated to produce this emission, the issue is providing some offspring, and that was what he was punished for.
So with this background, the WT spins a bunch of guilt around it with absolutely no scripture to support their position. So one could wonder why this is. When you consider it is pretty much a universal practice, then they cunningly know that they can induce guilt in someone doing it, and they can also induce a portion of the "guilty" to confess this sin breach of WT dictates and then have them in a place where they can be manipulated and controlled.
Some secondary damage could come from people who try to avoid this normal outlet to sexual activity, so they marry young and inappropriately, with all the problems that result from this. The Watchtower creates a problem that does not previously exist, and their is no need for it to exist other than making people fearful and subserviant to them.
The Catholic church and Mormon church have taught this same load of nonsense, likely for the same manipulative reasons, but isn't the Watchtower supposed to be better and not have the false doctrines of false religion? Apparently this is not the case. They are evil and anyone who loves their children will protect them from this spiritual cancer and abuse.