Christ, maybe I should pull all my open source projects that I no longer work on down from github for fear of people actually using it and then complaining when I don't maintain it indefinitely.
The dude released a script to the public under a free software license and people used it. If you think it's bad, fork it and fix it, otherwise don't use it, that's how the open source ecosystem works.
There are a dozen MarkDown implementations that are better than Grubber's piece of shit, and a couple that are actually nice. The lack of a decent implementation is not the issue. This issue is that Gruber is (regrettably but naturally) seen as the authority on MarkDown by a whole lot of people, and he's still encouraging them to use his insecure, bug-ridden disaster instead of pointing them in the direction of something that anybody outside of his use case would ever want to use.
He just needs to add a sentence or two to his website and he'll save countless developers a ton of headache. He just doesn't give a shit.
Yes, you should take down such projects if you have been informed of problems and can't or won't take the time to document them. Infinite maintenance is a straw man, because that wasn't requested. Only some civility was requested.
Your project can cost people a lot of time if it promises, but doesn't deliver. I just spent quite some time searching for a decent XSD parser in Ruby, haveing to wade through a score of projects that promise to do what I want, but turn out to be incomplete, buggy or otherwise useless to me. Many people will perform the same quest and together a lot of time is wasted, which could have been prevented if people would not just publish any damned thing, but would also take the time to properly document its state.
Open source projects without proper documentation, I can do without. This problem will only become worse in decades to come. I sure as hell hope github will start purging old projects with too many 'not useful' votes within the next few years. Otherwise it'll be a morass of stink where the gems can no longer be found.
I thunk the point he's trying to make is that if Gruber doesn't want to maintain Markdown, that's cool. However, he should announce that and let the community take over.
At some point there's no constructive criticism left to give.
His program is bad and he should feel bad