PDF with flattened layers reduces the usability of a PDF.
PDF with flattened layers that makes it much harder to extract contents.
Create PDF with layers.
Keep all text live, for accessibility.
Standirise on layers (Dielines, Artwork, Braille, Barcodes...).
The following steps describe how to view information about how to create PDF with layers:
InDesign and Illustrator,
Export to PDF → Choose the PDF Preset → Make Sure to Check the (Create Acrobat Layers Top-Level Layers).
The layers compatibility is up to Acrobat 6 (PDF 1.5)