[probably came into prominence with the appearance of the KL-10 (one model of the PDP-10), none of whose connectors matched anything else] The tendency of manufacturers (or, by extension, programmers or purveyors of anything) to come up with new products that don't fit together with the old stuff, thereby making you buy either all new stuff or expensive interface devices.
(A closely related phenomenon, with a slightly different intent, is the habit manufacturers have of inventing new screw heads so that only Designated Persons, possessing the magic screwdrivers, can remove covers and make repairs or install options. A good 1990s example is the use of Torx screws for cable-TV set-top boxes. Older Apple Macintoshes took this one step further, requiring not only a long Torx screwdriver but a specialized case-cracking tool to open the box.)
In these latter days of open-systems computing this term has fallen somewhat into disuse, to be replaced by the observation that “Standards are great! There are so many of them to choose from!” Compare backward combatability.