That’s the argument I usually hear as well. But a lot of the fidelity of such a high precision system is basically “wasted” reproducing the kinds of analog effects that exist at the edges of the ink meets paper part of writing/illustrating with a physical implement. Plotters with pens are still a commercial niche because the need for precise clean vector graphics to be mass produced in small batches of specific content (think custom topography maps with survey and drilling markers, or mission maps for a specific regional campaign, or other commercial line art work)

It’s sort of surprising there isn’t a well established reprap of plotting given it’s simplicity. The biggest missing piece is arguably the paper feed.

And as for an inkjet… why does a reliable printer need to be that good, I’d be pretty happy with a “higher dpi” pseudo dot matrix printer using a lift retract style mechanism and a hacked up refillable ink pen. Tapping out the art one dot at a time.

It’s not a bad argument for a lot of consumer printing use cases, but the “they need too much precision” never felt compelling to me given the breadth of printer technology both past and present.