If you are unable or unwilling to rebuild a browser from source, you've come to the wrong Web-site...
disabling an option is usually a prelude to removing it completely
It is not disabled. It was turned off by default — because it is useless for most users, as TFA mentions. Lots of other options are off by default — such as --with-system- foo:
Have you tested all the possible combinations of those '--enable-*' and '--with-*' options? Any configuration that is not tested and not supported is living on borrowed time.
What do you think will happen when they "accidentally" break the --enable-alsa?
Nobody building firefox for reasons other than purely masturbatory will ever bother to use an unsupported config for such a bloated, fragile and messy piece of shit.