From the /r/tor thread System33 posted a comment[0] originally by Alec Muffet explaining why Facebook set up a TOR service, which may answer some of your questions:
Why would anyone run a legal onion service?
Thanks Alec Muffett (OP) for the following summary copied from this comment
Understandably folk tend to think "Anonymity!" when talking about Tor Onions, but in rolling out the Facebook onion we established several clear benefits:
1. better and safer experience for people accessing over Tor: no interference by exit nodes, no bandwidth-contention for exit nodes, no use of exit nodes at all.
2. "good neighbour" - reciprocally, popular sites can unload themselves from eating up scarce exit-node bandwidth.
3. "a peace offering" - people (continue to) use Facebook over Tor; 3 years ago we saw 500,000/month, more recently ~1 million. Overwhelmingly we found (through measurement and assessment) that people using Facebook over Tor were ordinary folk wanting to do ordinary things. especially in times of political crisis. Providing a metaphorical "olive branch" showed that we value their use of the site.
4. Discretion & Trust. Onion Sites are considered to be about "Anonymity", but really they offer two more features: Discretion (eg: your employer or ISP cannot see what you are browsing, not even what site) and trust (if you access facebookcorewwwi.onion you are definitely connected to Facebook, because of the nature of Onion addressing; no DNS or CA shenanigans are applicable.)
Is this mainly intended for people from non-western countries who need a channel for free speech? Because apart from that I see no point in FB offering an onion service. If anonymity, discretion and trust are what I am looking for than surely FB itself is one of the least appropriate platforms for me.
Why would anyone run a legal onion service?
Thanks Alec Muffett (OP) for the following summary copied from this comment
Understandably folk tend to think "Anonymity!" when talking about Tor Onions, but in rolling out the Facebook onion we established several clear benefits:
1. better and safer experience for people accessing over Tor: no interference by exit nodes, no bandwidth-contention for exit nodes, no use of exit nodes at all.
2. "good neighbour" - reciprocally, popular sites can unload themselves from eating up scarce exit-node bandwidth.
3. "a peace offering" - people (continue to) use Facebook over Tor; 3 years ago we saw 500,000/month, more recently ~1 million. Overwhelmingly we found (through measurement and assessment) that people using Facebook over Tor were ordinary folk wanting to do ordinary things. especially in times of political crisis. Providing a metaphorical "olive branch" showed that we value their use of the site.
4. Discretion & Trust. Onion Sites are considered to be about "Anonymity", but really they offer two more features: Discretion (eg: your employer or ISP cannot see what you are browsing, not even what site) and trust (if you access facebookcorewwwi.onion you are definitely connected to Facebook, because of the nature of Onion addressing; no DNS or CA shenanigans are applicable.)
[0]: https://www.reddit.com/r/TOR/comments/792mfr/the_new_york_ti...