No, it's still a weird scope creep. Browsers can view a lot of things (HTML document, various pictures, sounds, videos), but they don't typically include editing functionality.
So this seems to make a lot of sense to me and I'll be glad to have the functionality, especially when PDF functionality is such a mess in the general world (lots of barely-working software).
Not true. The original Mozilla Internet Suite was a combined browser, email/newsgroups client, and web-page editor. It was an open-sourced version of Netscape Communicator which did the same things. Seamonkey is the modern fork.
Firefox is the result of a project to cut down the Mozilla suite to something smaller, simpler and more focused, but its parent program and direct ancestor edited text, HTML, and did other read/write stuff like messaging, calendaring, etc.
> The first web browser - or browser-editor rather - was called WorldWideWeb as, after all, when it was written in 1990 it was the only way to see the web.[1]
Remember WordPerfect? When you press F12 in Firefox, you have essentially the same thing as the reveal codes pane in WP.