2d printers need to be a lot more precise. 300dpi means each dot is placed with less than a tenth of a mm, and that’s not even particularly impressive for a 2d printer. 3d printers get away with a lot more slop than that.
That’s only talking about greyscale. Color requires precise alignment of the cartridges for at least 4 base colors (higher end photo printers have even more) , and the mix of those colors must be carefully controlled to get accurate output.