Displaying nominal data with a line graph Recently I stumbled across a line graph displaying a contingency table which I found was a very powerfull visualization. In my opinion it is very seldom that nominal data is displayed this way; usually plots like a bar plot, mosaic plot etc. are used (see here or here for example).
To illustrate I provide a) a bar plot, b) a mosaic plot and c) a line plot for the same data. The Titanic data shows the frequencies for the variables Survived (yes vs. no), Sex (males vs. females) and class (1st, 2nd, 3rd and crew). I only included adults in the plots.
a) Bar plot

b) Mosaic plot

c) Line plot

The line graph seems to clearly display what is going on, e.g. more males than females in total, class has a big effect on survival and so does sex, etc. Drawbacks of the line graph I can think of:

*

*The line goes through area were no category exists, e.g. there is nothing between first and second class. But: this seems to highlight what the changes between the categories are. It`s kind of like a piecewise regression which shows the slope between two adjacent categories.

*It is confusing if we would include confidence intervalls here because the ci must not follow the line. But: Mosaic plots can not display ci either.

What are other drawbacks of the line graph here? Considering the rare use of the line graph in this case I guess there must be more. Or am I wrong and line graphs are a legitim/ common way to display nominal data?

Remove the lines and make the shapes larger and you'd have a "dot plot". I'd say that is a common way of visualizing this type of data-- using the markers to show the points without the "area" of a bar plot potentially confusing the viewer-- but without the unnecessary (and potentially misleading) interpolation done by connecting it with lines.
Often, these would have the axes flipped (coord_flip() in ggplot2) and then you would sort the axis so that non-ordinal values were sorted in ascending or descending order, depending on what were emphasizing (putting the "most interesting" groups at the top of the Y axis).
A version of that with more pizzaz is the "lollipop" chart which is simply the dot plot with a thin line drawn from the axis to the dot. Those lines don't add anything except aesthetic value. They add "chart junk", decrease the "data-ink ratio" but they do look cool sometimes. For someone who hasn't seen my charts besides bar graphs it may help them intuitively understand how to read the dots. Here's an example that looks nice which was made in excel  (https://policyviz.com/2016/02/04/lollipop_graph_in_excel/).
