If this tool isn't of interest to them, why are they reading the comments and then going further to bother commenting here though? Why did it ever have their interest to lose it? The very first word in the title is 'git'. If they don't use git then why are they in this part of town?
It's like if there was a post on some other forum about kayaking and I went out of my way to say 'sorry this isn't interesting to me because I'm into cycling and don't like kayaking'. Imagine what it would be like if every HN user went down the front page and commented in every thread that mentioned a technology they don't use 'sorry I don't use this technology so this post is useless to me'.
Yes I suppose it's a totally valid opinion, but it's just entirely useless to offer it here.
The issue with the previous comment was entirely due to phrasing, in my opinion. A "Show HN" of an open source project is a gift, the socially acceptable response would be to thank and politely refuse, and maybe suggest an improvement.
"This seems interesting, but I wish it supported other VCSs - you will have to claw Mercurial from my cold dead hands!" would have made the same point, but it'd wouldn't sound like the developers somehow owed something.
@stephenr: Well then you'll miss stuff like that. I honestly recommend checking out git in depth in your spare time. Just like learning lisp it will increase your programming skills even if you never use git in production! Maybe you come to love it for the same reason I do: incredibly well done architecture under the hood. It's the first time I could completely grasp what a VCS wants to do and how it's achieving its goals.