Oh, actually it does something: it I write [[assets/file.pdf]] instead of [file](assets/file.pdf), I can Rename Symbol. But, if I place the cursor on [[assets/file.pdf]] and "Rename Symbol" (say I want to rename it to file2.pdf), it actually moves vault/assets/file.pdf to assets/file2.pdf.
i.e. it creates a folder "assets", that is different from the one under "vault"
And another weird thing: If I rename [[vault/assets/file.pdf]], it does rename the file this time, and keeps it under vault/assets, but changes the link to [[file.pdf]] after renaming. I can't win 😢