Weaknesses of iOS: Annotating in iBooks

This is how the test goes:

– Take a page in Safari you want to keep and pass it through the ‘Save PDF to iBooks’ sharing action.
– You automatically get the new PDF opened in iBooks, but the only thing you can do in it is inserting a bookmark.
– Don’t try to highlight text, add an arrow or a square or write a comment; such actions aren’t possible.
– You cannot even send this document to the Preview folder in iCloud Drive.

Is that a weakness or a conspicuous failure?