As you can clearly see from the axis labels, they are not plotting standardised or indexed data, what they did was hand picked a rescaling that makes the plots line up very nicely.
Further, it is simply not true that weight is a perfect function of neck size, so you shouldn't make a plot that implies that.
>what they did was hand picked a rescaling that makes the plots line up very nicely
I bet dollars to donuts that's what a stardization would show too, unless I'm missing something. It would show an even more perfect lining up because it would line up the line ends.
Wish I could test it. Wish pandas had a read_image function to get data from line plots like it has read_html.
The reason it's hard to pick which chart is better is that both charts are far too detailed for the tiny amount of information they convey, which is "both values shrank over time"
Can you further explain the frankly astonishing statement that you find it hard to pick between a plot showing a false equivalence and one that doesn't?
Further, it is simply not true that weight is a perfect function of neck size, so you shouldn't make a plot that implies that.