Surely we want competitors in this area, there's obviously a need for it and a number of tools competing on features and price can be good for consumers?
To answer the parent, Adobe technically does have a competitor in this space, though it's not focused on bootstrap and it's kind of complicated: http://html.adobe.com/edge/reflow/
As someone with a product in this space, I'm confident each of the current offerings listed above will diverge sufficiently in the future, specifically in their target audience. It's still so early though.
And Max (yesimhuman) is right: it's pretty early, and we're all approaching the problem from different perspectives.