It doesn't need to be. (Why the italics?) In fact I don't give half a crap about the implementation details of how it works. All I want is to be able to drag a little diagram from a paint program into my code editor and have it there in the code and then when someone else looks at the code they see the little diagram, too. Whether it's implemented by a "binary object", or by adding an additional XML file, or by a magical monkey from heaven reaching down and placing it there, I do not care. I'm talking about a feature I want to use, not about nitty-gritty implementation details.
As for "shunning other editors", well, frankly, why are we as an industry bending over backwards to support people using editors from the 1970s? Do you think Ford still builds cars with imperial measurements just so Old Bob the mechanic can keep using the tools he bought when he went into the field in 1968? No of course not, that's stupid. But that's exactly what our industry is doing.
As for "shunning other editors", well, frankly, why are we as an industry bending over backwards to support people using editors from the 1970s? Do you think Ford still builds cars with imperial measurements just so Old Bob the mechanic can keep using the tools he bought when he went into the field in 1968? No of course not, that's stupid. But that's exactly what our industry is doing.