That's one of those things...., for example, in England they had Lemons, and tea, but it appears from the diaries and journals of the time that it took more than a century of tea being well known in Europe and England, before Catherine the Great of Russia introduced the idea of adding lemon juice to tea.
Contact with China was made by the Portuguese in 1517, YET as late as the 18th century, with the British trading in Canton without interruption for the whole century, after all of that contact..., nobody ever wrote about Europeans adopting what we call today "stir fry" or the Wok as a cooking tool. The sailors and their officers HAD to have seen them used..... they also had to have seen a Chinese box bellows...not a European thing, however.
All of the technology to create a "reflex" style recurve bow (often today called the Mongol Bow) existed in England and Europe, but even after the Mongol invasion as far as Hungary, Romania, and Poland.., where the Europeans learned first hand about the effectiveness of that bow, and its use on horseback....Europeans never adopted that style of bow. I mean, they saw it, AND at least a few of the Mongols had to have been killed carrying that style bow, so they had to have had examples to study, right? However, by Agincourt, more than two centuries after contact with the Mongols, neither side was using it, nor were they using mounted archers....
Nicholas Appert took 14 years from 1795 -1810 to put together a glass container, with a cork held in place with a wire cage (the Champagne bottle with the same system was invented in 1632) so that when heated in boiling water for a certain period of time, the contents would not spoil...., and canning was invented. 178 years from when the elements of the technology existed to when it was finally put together. Now Appert was a chef, not a scientist, so what kept the scientists from doing it sooner???
History is rife with examples of stuff that could have been, but for other reasons, simply was not developed from what we today think is "obvious". So while I think such a shelter is "obvious", and simple, it's just not recorded as existing. Could've... sure... so what?
LD