Web Browsers Are for Rendering Web Page, They Shouldn't Become PDF Editors
The UNIX "philosophy" (or POSIX way or whatever) is associated with "atomic" programs that do one relatively simple task and do it correctly (or well). Then, those programs can be chained (e.g. outputs piped as inputs) to make up larger and more complex programs, whose pertinent components will be actively maintained, improved, polished, patched etc. That "philosophy" has generally worked well; that's why the "UNIX way" has lasted much longer than Apple and Microsoft have existed.
What about a Web browser's "philosophy"? Does it have any? "Instead of making the browser better," an associate notes, this is what Mozilla does next (more attack surface and room for defects in the code):
Typical Mozilla.
What's the correct "philosophy"? Firefox should open PDF files in the operating system's PDF viewer (which may also be an editor). There are many reasons to do things that way. If "Firefox 151 helps you edit PDFs" and if "Web browsers are editors" (remember Netscape Composer?), why stop there?
If browsers are now editors of Web pages and of PDFs, then why doesn't Firefox have a built-in GIMP already? Why does it not have a built-in spreadsheet editor?
Netscape tried this bloatware approach.
"Don't download LibreOffice. Firefox is better."
Later on Mozilla - with its bloated codebase - is encouraged by a 'generous' Anthropic (thieves) to help do marketing for Mythoslop - arguing that slop is good at finding bugs (humans with fuzzing tools can find them just as quickly and avoid false positives which waste humans' time).
Linus Torvalds is quickly learning and speaking about this. █
Image source: Opened red swiss army knife