i think 'onboard' might refer to the wider context of using a tool in say, a research group. it's not just you learning the tool, it's about how the group uses the tool and the historical developments in place.
It's just a tech business language mannerism. People use it for the same reasons they use "price point" instead of "price", or "usecase" instead of "use", or "form factor" instead of "size": to show that they belong to the tribe, and to sound clever while saying something that could be expressed more simply and elegantly. The jargon adds nothing, except cringe.
People who code for a living are used to regularly teaching themselves new things, but there are lots of folks in other corners of the organization that expect to be taught / onboarded, and it's not an entirely unreasonable expectation. I think the word "onboard" implies a cost will have to be paid (e.g. time, money, man-hours, hiring new talent, etc.), and that's what the parent poster wanted to emphasize.
worked with a lot of techs this way. They get mad if you show them what you're trying to teach them shows up with very good instructions on the first page of google. At least half of them get pissed off :)