“You remember how our entire team left last year because they were fed up? Those were all the people with knowledge of the system.
You also remember how you gave us a budget of 50k to hire replacements? Well, we used it on one developer, and he’s left university this year, so doesn’t even know what jQuery is, much less how to work on that system.
That’s why changes are slow.”
Much preferable to not shame him like that and just summarize it as “It was built 4 years ago with jQuery.”
What the exec needs to hear is "this is built on out-of-date technology that is slowing us down and to fix that we need to be given time to migrate the application to a modern technology".
Problem + proposed solution + no irrelevant details like the name of the technology.
However, my experience has been that management generally just doesn't care no matter which version of the explanation they are given.
Either way, I'd be thrilled to be treated like an engineer/craftsman. That would be a big step up from "interchangeable cog".
Also, I'm not clear on what's wrong with "it was built with jquery and no one has touched it since 2014". The fact that the system is built using an archaic technology, that technology is inferior to current technology, and the engineers are not familiar with the code base is completely relevant to how long it will take to make changes.