I think it's 2 factors.
First, indeed the sentiment changed radically between now and then. For some reason, this subject has always attracted irrationality on HN. Back then any comment vaguely positive about cryptocurrencies would accumulate downvotes, now threads are full of clearly invested shills (you can see it in this very thread).
Secondly and more specifically, Stellar, being a simple Ripple fork with an equally dubious token distribution, was a weird fit for Keybase.
MobileCoin, while having some of the same downsides (federated, centralized token holders distribution) has a more interesting design, and is closer to the actual cryptocurrency/cypherpunk spirit thanks to its fully private transactions and balances.