What people search and post about
Searches include flatten PDF form, make PDF non-editable, and questions about filing combined forms without fields breaking.
Why it piles up
A folder of fifty signed W-9s or client acknowledgments still has live fields until flattened; touching each one in a desktop app is not a good use of staff time.
Batch speed
Upload, flatten, download. Use after Autofiller batch runs or before Automerge when the court or portal requires static pages.
Tradeoff
Flattened PDFs lose easy field edits—keep an archival copy of the fillable version internally if you still need amendments.