You base this statement on a sample size of N=2. On many Show HN submissions I tend to see just the opposite, people act as test users/engineers/etc for free and then write their impressions.
The problem that you faced, I think, is one I (and others) have noticed before: HN response dynamics is not stationary, i.e. it tends to change quite a bit with time of day (different moods or geographic audiences?), time of week (TGIF or the reverse effect), and even by time of month (full moon?). There are many posts analyzing the optimal time to post.
Having your project (or thoughts) bluntly criticized publicly can be painful. One solution could be: (i) Closely read and re-read comments offering constructive criticism (ii) ignore "snarky", etc. comments but note their ratio to the constructive ones, if the SNR is low then you have to think what on your product triggered such an outpouring.