Firefox Sync disabled - why?

[Jakub Kądziołka]

Dear GNUzilla developers,

I recently switched to Guix System as my main operating system, and
noted that instead of Firefox, the package manager contains IceCat.
IceCat is working just as well as Firefox for me, with the single
exception of Firefox Sync - the feature is just not available, and this
seems deliberate considering the steps one needs to take to reenable it:

- In browser/confvars.sh, set MOZ_SERVICES_SYNC to 1
- Recompile
- In about:config, set identity.fxaccounts.enabled to true

I'd assume that this has been done to protect the privacy and freedom of
your users, but after some research I believe that this decision has
been done with incomplete information:

- The feature does not violate users' privacy; considerable effort has
  gone into ensuring that Mozilla is not in a priviledged position [0]
- No proprietary JavaScript is required [1]
- The feature is not SaaSS - synchronising data between devices is not
  something that could be done locally. At best, Mozilla could provide
  what's necessary to run your own server. In fact, they do! [2]

So, what is the rationale for disabling Firefox Sync? Did I miss
something in my analysis? Would it be reasonable to expect this to be
available by default?

Regards,
Jakub Kądziołka

[0]: https://hacks.mozilla.org/2018/11/firefox-sync-privacy/
[1]: https://github.com/mozilla/fxa
[2]: https://github.com/mozilla-services/syncserver