[trelane]

> Docx is similarly open as PDF.

This is not true, as far as I can tell.

> PDF has an edge here in practice because most use cases are read-only

I think many folks would be extremely happy to have full-fidelity read-only access to Microsoft formats without having to have Microsoft Office.

On the other side, it's _extremely_ common to both produce and consume PDF without over touching an Adobe product.