If you look at that thread, people are relying on a company called Reserve, that essentially issues its own currency (a 'stablecoin'). This is the part that I don't get—how is it cryptocurrency when you are relying on trusted third parties?

Yeah that’s a good point, even the DAI stable coin which is touted as the most decentralized is actually backed by a lot of USDC

I think their website answers your question: https://reserve.org/protocol

I've been trying to find coverage of Reserve from non-Bitcoin/Cryptocurrency publications - basically because I don't trust any of those publications - and I've not been able to find anything convincing yet.

This is a general problem I have with crypto stories: every crypto coin has a built in incentive for people who hold it to hype it so it's really hard to tell if actual regular users are finding it useful yet.