Motivation for asking to use a modified version of the viewer

[stijnherreman]

https://github.com/mozilla/pdf.js/wiki/Setup-pdf.js-in-a-website says:

The viewer is built on the display layer and is the UI for PDF viewer in Firefox and the other browser extensions within the project. It can be a good starting point for building your own viewer. However, we do ask if you plan to embed the viewer in your own site, that it not just be an unmodified version. Please re-skin it or build upon it.

What is the motivation for this? Is it a technical reason? Or are you hoping to encourage people to build more viewers? Please clarify.

[yurydelendik]

What is the motivation for this? Is it a technical reason?

It's multiple reasons. In numerous occasions, people mistakenly called defects in custom deployments as Firefox bugs (since PDF.js demo viewer looks nearly identical to PDF Viewer). Security, see #6916. Also, people are asking for configuration that is not easy to invest in (e.g. skins, adding/removing toolbar buttons, etc.) -- while it is fixable it requires lots of investment in the support.

Or are you hoping to encourage people to build more viewers?

Yes, this too.

Closing as answered.