You vastly underestimate the level of bureaucracy that can exist in the biggest Java users of this planet (namely banks and public administrations): in these organization (at least a few years ago, the Solarwind attack shows it may not be the case anymore) every single dependency you want to use must be justified, and then is audited by a dedicated team, which ends up handing you the validated .jar.
It was a common development practice in these entities (I was working as a contractor, for different customers), most of them have been using computer programs at there core long before the internet went mainstream.