I don't find these plots misleading. A line plot emphasizes slope and changes in slope, rather than the absolute heights of the data points as a bar or area plot would; so it's more important to have consistent vertical and horizontal intervals.
Supposed solution A changes from 10000 to 10001 and solution B changes from 10000 to 10000.5, emphasizing only the slopes doesn't tell you that this changes may be insignificant.
The given link above (How to lie with data visualization) gives axis truncation as a very first examples.
Indeed, and I disagree with the article regarding axis truncation of line plots, in this context.
I'd also be careful with terms such as "insignificant" when we're talking about data. Suppose that tiny difference were significant. Depicting it as a bar would completely mask the difference, and truncating the axis would give the false impression of the bar's height representing the total magnitude. There'd be a similar effect with a line plot, but the line focuses on continuity and de-emphasizes height: it's not as big of a problem.
There are myriad ways to tell stories using data, and there are myriad ways to tell misleading stories using data. Each type of plot has distinctive properties that make it more or less appropriate to be used/manipulated in certain ways, so I'd hesitate to apply a static set of rules indiscriminately.
Just because axis truncation is in the lier's toolbox doesn't mean that every use of axis truncation does, or intends to, misrepresent the data or is inaccurate.
