I don't get Gruber's reaction. These guys have done a huge favour for Markdown, resolving real-world compatibility problems with the first ever unambiguous spec

I don't get Gruber's reaction. These guys have done a huge favour for Markdown, resolving real-world compatibility problems with the first ever unambiguous spec. Surely this is a good thing? If Gruber really wanted Markdown to succeed, isn't this the right direction? If multiple independent implementations of an idea start appearing, sooner or later this is going to happen. And at that point what control can you claim to have other than the name? These guys presumably have their own code, and I'm pretty sure sites like reddit have a heavier investment in Markdown than Gruber.