Well, Ian, a technical camera is not a press camera, and a press camera is not a technical camera despite folks trying to interchange them. The Speed Graphic was actually made from 1915 to 1973, but was not so commonly used in the early and later days.
Yes, you are correct, in a way, I was talking from a USA centric viewpoint, but it was an America camera I was talking about. And there was an American equivalent to the Linhof & MPP, the Meridian. None of those cameras sold anywhere near as well as the Speed Graphic, even today you can find 100 Speed graphics for every one of those cameras, at least in the USA. At one time in the USA just about every professional photographer owned a Speed Graphic. In the news, weddings, sports, industrial photography areas they were the choice probably 1000 to 1 over everything else. In baseball and horse racing the Graflex SLR was more popular, but those were used from the press boxes with 3000mm or longer lenses (Big Berthas, as they were called), from the sideline the Speed Graphic was king in those areas too. When you ignore the brand, there were hundreds of competing brands out there, and just talking about press cameras "ubiquitous" is not too strong a word.
Prior to 1955 in the USA National Geographic was about the only magazine that accepted 35mm color slides for publication. From 1955 to 1965 many more publications would take 6x6 transparencies, only after that did 35mm really become acceptable for publication. Industrial photographers were still using the 4x5 press camera for most of their work into the late 1970's when the rest of the world had gone to their Nikons. Through the 1960's & 70's Nikon owned the publishing world, the Nikon F & F2 probably being preferred 10 to 1 over the other brands. Compare that to the 1000 to 1 for the Speed Graphic.
Yes, in Europe the Rolleiflex, and then the Leica were the choice for a long while, but for publishing, no camera was used more than the Speed Graphic. I would wager that is probably even true worldwide, although for a shorter period, there are a heck of a lot of Graphics floating around outside the USA.