As far as I can tell, it's probably healthier to think of leftism as a bunch of loosely collected strains. Some more authoritarian than others... and I think people pick and choose which parts they wish to internalize.
Personally, I think there's lots of evidence that you can create institutions where experts are empowered to influence decisionmaking (and to manage their own worklives with dignity), but don't dominate over others. And I also believe it's not trivial, just like running a corporation or government today isn't a piece of cake either. (As evidenced by the management/leadership section at the bookstore, built through sometimes painful trial-and-error.)
Slightly offtopic, anarchist prof Mark Lance had an interesting talk* where he observed that revolutionary movements can be nicely egalitarian in structure, but generally lead to very hierarchical societies once they win power. Something to be careful about...
Oh, I gotta run, but Semco comes to mind as an apparently very successful capitalist corporation, explicitly influenced by anarchist thinkers like Bakunin... though of course such ideals have strong tension with capitalism.
* http://www.radio4all.net/proginfo.php?id=8655
Tayssir