I think that's implied when a mainstream news outlet writes about it, and not some tech magazine.
> In general I think that the press and the general public only becomes aware of these things long after they have reached a dominant market position and are employed almost universally.
which seems evident, here. ARM becomes dominant -> Guardian writes about it -> the general public learns about it.
Damn it, i still recall when people got hot and bothered about getting updates for their Nokia Series 40 phones over the air. Before than you only got it done if it was obviously broken, and to do so you brought it to the service desk of a nearby store or some such.
Exception being when it affects the journalists directly, as is the case with how the media followed Apple closely even when they were a bit player in the computer world. This because media production had for better or worse de-facto standardized on Apple.
Thus when Apple branched out into the consumer electronics world, they wrote about it. This even though Apple was hardly the first, and their offering very much wedded to the Mac.
In general I think that the press and the general public only becomes aware of these things long after they have reached a dominant market position and are employed almost universally. It's probably sure that even now many companies that are almost unknown to the general public are working on technologies and products that will change entire markets in the future.