Of course they can be disabled. But sites are not all built the same way, so there isn't one silver bullet we can tell you about to disable them everywhere. On mobile it's even more difficult because access to browser plugins is more limited, along with developer features within the browser.
I also use FF on Android, and until recently was also using Reddit. There isn't a good way to remove that bar.
So what you're suggesting works in theory, but not in practice. There are times when simply ignoring bad actors or voting them down within a community is not enough to stop them from misbehaving. Try ostracizing a botnet. Or nicely asking trolls to stop posting racist memes. It won't work.