OK, I get it now: "The article conflates two parallel branches with shared glass/vacuum know-how when it starts talking about diodes."

The article is right that the vacuum tubes, whose first application were the Edison lighting bulbs, then the Fleming diodes, which evolved directly from the incandescent lighting bulbs, are descendants of the Geissler tubes.

During the evolution of the Geissler tubes, the techniques of making efficient vacuum pumps and of sealing well the glass tubes were developed.

Only when the pumps and the glass tubes had become good enough, it became possible to experiment with the first vacuum tubes, by omitting the filling of the tubes with low-pressure gas.

Without the decades of playing with Geissler tubes there would have never been any incentive to develop the technologies without which making vacuum tubes would have been impossible.

Therefore there is no doubt that what the article says is correct, i.e. that the vacuum tubes are descendants of the low-pressure gas tubes, which were initially known as Geissler tubes.

So the vacuum tubes are a lateral branch of the development of the low-pressure gas tubes. After splitting, both branches have continued to evolve in parallel until they both have been replaced in most of their applications by semiconductor devices.

While vacuum tubes were better known by the general public, because they were present in things like radio receivers or TV sets, which many people owned, in industrial applications gas tubes have always had a similar importance to vacuum tubes.

Even the first electronic counter, which can be considered the ancestor of all electronic computers, has been made with gas tubes, not with vacuum tubes. (The first electronic counters were made to count the pulses from detectors of nuclear or cosmic radiation, for which the existing electro-mechanical counters were too slow. The circuits developed for this application were the basis for the development during WWII of the digital electronic circuits used in the first electronic computers.)