I used Orgmode for years, but I think fundamentally tieing your markup to your editor is kind of a bad sign... I'd be curious to hear counterarguments though. I think the primary reason it's tied is because you sort of can't make standalone ELisp apps (or at least nobody does). Otherwise you'd just have an `org2html` and `org2pdf` application at the command line. Alternatives like Asciidoc are not perfect, esp for li…
Org is hardly more tied up to the editor than any of the many other formats people use – all of these have more or less complete editor support depending on what features you need (e.g. if you start doing fancy literate programming in markdown, or azathoth forbid, try commenting out lines, you'll find spotty support in at least some of the existing implementations). And if you like the full combination of features that Emacs+Org gives you, you'll be hard pressed to find another environment to replace that, so ... why bother?
(OTOH if you only need some minor part, like html export, and you have to work with people already using other formats, then those other formats might be better.)