When creating dumbbell charts or lollipop charts for example, it would be nice if we could add centered gridlines that will help guide user eyes to the right dimension label. This idea can be generalised to have more formatting options for dimensional axes.
source: Lisa Charlotte ( I’m surrounded by old people | Uncharted )
Current work around (dot charts ONLY):
When plotting simple dot charts, it is possible to work with a Calculated Field and Dual Axis bar chart to mimic the on-center horizontal gridlines. However, this is a hack that comes with certain limitations. For example, there are limited formatting possibilites: the minimum width is still relatively "fat", no dashed lines possible etc...
For more advanced dumbbell charts in Tableau, this hack is not possible due to the specific rendering of the Gantt mark.
Source: Communicating Data with Tableau, Ben Jones, Figure 3-11. The formatted dot charts