Draw can open PDF files. As the LO team states, Draw is neither a PDF editor nor a PDF viewer, and Draw does not support text justification and proper line wrapping, so Draw does not guarantee the correct appearance of the document. Then what is the purpose of opening PDF files in Draw?
Some use it for minor editing.
To make a minor change to an existing PDF can be enough to avoid having to rebuild the document. For example, a company shifts premises so the address needs to be changed on a pdf, or an image needs to be replaced but the original document is not available. Obviously, it is better to recreate the document but time constraints in businesses and life often demand compromises.
PDF is not a text processing format, it is a page display format.
This means the document has been formatted and laid out by some applications before being exported to PDF. PDF made it equivalent to a graphical set of objects. Being graphics, the only LO app which can handle it is Draw.
Converting back automatically to some text format is next to impossible because a lot of information has been lost in the process. For example, justification has been replaced by explicit positioning of runs of characters or even individual characters. There are no longer continuous sequences of characters to form paragraphs but sets of smaller-than-one-line groups of homogeneous characters (there may be several in a display line).
All this is done so that a PDF viewer has no complex task: no justification (already positioned), no line break (already determined), no page break (already done), etc. The PDF viewer can then be very simple and fast.
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