פירוש על ברכות 105:28

ONE MAY NOT RECITE A BLESSING OVER IT. When one uses perfumed oil in middle of the meal, he does not recite a b’rochoh for benefiting from the fragrance of the wood. But he is benefiting from the oil! Rashi says that he does however recite the b’rochoh that Hashem created sweet oil. And that which we said earlier in perek Kaitzad M’vorchim (43a): this pressed oil, we recite upon it “He who created fragrant wood”, that is when he intends to smell the fragrance and it is not speaking of when one uses it during the meal to cleanse one’s hands.

Because it is used as a disinfectant and not for smelling.

On the hands after a meal, the oil being mixed with spices. In the case of the oil, it means that the benediction is not "Who createst fragrant wood" but "Who createst fragrant oil"; see fol. 43 a, p. 280.