FYI I don't think Signal cares much about anonymity (sadly). I've seen several discussions on their forums where admins have even been hostile to people asking for it. I love Signal, but its community is toxic and I really wish the devs would move a bit faster. I know it is a tall order, but that's what Moxie argued in his "The Ecosystem is Moving" talk (we can't have decentralized because you have to move fast and adapt). There's a lot of low hanging fruit that Signal just seems to ignore.
However much they care or don't care about it, the salience of this NDSS paper is that Signal has a relatively complex anonymity feature that no other mainstream messenger has (the ability to cryptographically authenticate a message that can be delivered via the service without the client authenticating to the server), and it's susceptible to some straightforward network timing analyses.
There may be any number of other reasons to believe that Signal doesn't care enough about anonymity, but with respect to this paper, the most you can say is that they don't get full credit for an extra credit anonymity project they did.
Oh, I use Signal and still push my friends and family to use it. I'm not arguing against it. You're right that it is still a great app that does things others don't.
As to anonymity, I'm more frustrated with the community being hostile against other community members asking and pushing for it. I do understand that the community isn't the signal team, but it is their official community so it does set the tone. Especially since they specifically note that that's the only community they pay attention to. (e.g. GitHub bug reports should be on community)
As for non-anonymity stuff, there are quite a lot of extremely low hanging fruit that is weirdly not available but highly asked for. Like having to go to https://signalstickers.com/ to get stickers? This should clearly be accessible through the app (or they should be hosting their own). Delayed messages are thankfully here but took forever. For some reason forwarding messages on phone vs computer has different behavior (I can edit from the computer; the preferred method). Still can't find messages associated with media. Can't star/favorite messages. These are very important features that each could be done in less than a weekend so it just seems odd.
I do want to see Signal be more used and I want to see it grow. I love it and advocate for it, but that also doesn't mean I'm not going to be critical of it when it is having issues.
Shooting for the extra credit is the assignment. Nobody uses Signal as an actual chat app, there's far better chat apps including Telegram. The presented hyper-emphasis on anonymity is their only value.
To my knowledge they don't emphasize anonymity at all. Instead they emphasize privacy.
The distinction being that anonymity is when nobody knows who you are and privacy is when nobody knows what you said. You can technically have both but most systems make a compromise of one or the other.
