Is 勺 really the phonetic component of 的?
Modern Chinese has underwent many pronunciation changes since characters were first invented and phonetic components often reflect words as they were pronounced in Old Chinese rather than modern Chinese.

The pronunciations of 的 and 勺 were much more similar in Old Chinese. This link explains:


  的 and 勺 had roughly similar pronunciations in Old Chinese; Baxter-Sagart reconstruct 的 as *t-lˤewk, compared with 勺 *m-t-qewk.


Note the that 的 character as originally used means "target" and is pronounced dì in Modern Mandarin. In modern times, it was borrowed to also represent the genitive particle de (this usage ultimately descends from 之; refer to this previous question for more information).

A few other modern Chinese languages still preserve the final -k in both of these words. For instance, Cantonese has the pronunciations dik (IPA: /tɪk/) and zoek (IPA: /t͡sœːk/) for 的 and 勺.