Not quite true; zcash is best-of-breed and works well. Dead on for this being a devastating error though. I regret advocating Signal, and this destroys Moxie's credibility in my eyes. A shame, because the Signal team did good work to bring strong encrypted communications to the masses. Instead of focusing on fixing usability, stability, and group messaging that scales, they push this in (which nobody asked for) just to make a few people rich through network effects.
Mobilecoin is a pre-mined Monero rip-off (that Moxie has clear links to) with centralised Ripple-esque consensus, and puts UK Signal users into uncharted regulatory waters. Downright sleazy.