Well that's a shame... The whole idea of this new "Launcher" was to take authentication away from 3rd-party launchers and give it back to the vanilla launcher. Instead what we get is a new "app" that requires a 3rd-party account to even use.
That's what's odd about it to me. Curse seemed to go out if its way to satisfy Mojang by using Mojang's own launcher, which maybe gives an impression that they care about your privacy/security. Yet after poking around CurseVoice's Friend Sync I found that they don't mind to probe your Skype/Steam/Battle.net for users to invite, the latter of which in particular appears to be in an unofficial and questionable manner. Curse won't comment on it, either, despite it hitting the front page of the subreddit, someone tagging Kaelton in a comment, and me later tweeting at them, to no response whatsoever. After the fact it was brought to my attention that Curse has done things in the past with their launcher apparently without making companies aware of their actions first, and it led to them getting in a bit of trouble (like the LoL overlay being considered a cheat). Some people even claimed they were banned by Riot for using it, but I can't confirm that they weren't just cheaters, so I don't know what to believe. All I know is that it makes me wary to use Friend Sync if it could jeopardize my Steam or Battle.net accounts.
Meanwhile, you can't really ask Blizzard if it could potentially lead to a ban, because trying to communicate with them about anything that's not a multiple choice question in the support page is a waste of time. And that's not to mention the people you end up dealing with accusing you of being part of a lynch mob just for posting anything that's not in a positive light about Curse, since you apparently have to either love them or hate them.
If I'd known such a simple question would lead to such frustration and uncertainty I probably wouldn't have bothered looking deeper into the launcher in the first place.