Some companies want resumes submitted as text or .DOC, for easier keyword searching perhaps. Or to avoid viruses? So the recruiter may OCR the PDF, then "improve" on it.
Apparently everyone keeps forgetting that PDFs are editable.
Certain tools, such as Word and LibreOffice, make it a bit easier as most of the source text is in the document, others like LaTeX end up looking like garbage through machine processing.