"Do we know Ed doesn't suffer from depression?"
This in fact happens on HN from my observation frequently.
It goes like this.
Someone says something and if people don't agree they downvote and sometimes say something nasty in return.
Someone write a "Please Help" plea on HN and all the sudden everybody is nice and considerate and rolls out the red carpet (at least time times this happens that the plea gets voted up).
People of course don't know if the person they are being nasty to is suffering from depression, having a bad day, just got fired etc. Unless of course they specifically announce that fact in the "Subject" of what they write (or in a blog post etc.)
No need to ask why that happens (why people are nice when someone lays on their belly asking for help) because it's obvious. The question is why are people so quick to be a "dick" if someone doesn't reveal any weakness.