Don Norman explains this in the latest edition of The Psychology of Everyday Things (amazing book on product and design, btw). Sometimes, it can take centuries before tech goes from idea to everyday reality in the hands of ordinary people. For example, the videophone was depicted in a famous illustration as early as 1879 [0] but it's only in the past two decades that mobiles have made them somewhat ubiquitous.

[0] https://en.wikipedia.org/wiki/Telephonoscope#/media/File:Tel...