I see at least two advantages: compared to hydrogen they are not flammable and compared to helium they don't require a limited resource.
Hook up a vacuum pump to a flask. It isn't going to rise as the air is pumped out. Edison's light bulbs did not float.
That was my original question: is it technically feasible to make such a chamber from light enough materials (my first guess would be some carbon tubes supporting a carbon fiber tarp or something like that.
> Edison's light bulbs did not float.
One could argue that it was too small (of course I imagine making a massive lightbulb would not make for a good solid structure, also glass is heavy). A hot air balloon does not float either if you lest it too much.