There's no dropping the text manipulation thing, the setting on Firefox is completely under Firefox developers control, and has nothing to do with what the button does somewhere else. That's like saying it's a Windows problem that a shortcut is different by default on a given program, complain to Firefox devs if you think the default should be enabled.

Also you're making a huge deal out of something that's two clicks away, middle mouse button works as a navigation tool on Linux just like it does on Windows, additionally it provides extra features under some circumstances.

So to recap:

• You claim it should be a navigation button.
• I told you it's a navigation button as well
• You claim it doesn't auto-scroll
• I told you it does
• You claim it's not on by default
• I told you it's the programs option what's the default
• You claim this is still Linux's fault

Honestly it's always the same, people claim Linux has a problem whenever a third party program does something. Linux is not perfect, but I have never seen anyone who doesn't use it actually list any of those problems, they always point at third party software as proof that Linux is bad.