Also perl is apparently as fun for humans python which I also find suspect after maintaining perl 5.x code.
Turns out this subjective made up graph is subjective and made up I guess.
When people talk about a language being 'fun', they need to distinguish between writing something new for the first time vs maintaining something or figuring out someone else's code.
Sometimes I mumble under my breath that Ruby is Perl for the 21st century - gleefully creative hackers leaving behind overly clever code for far less happy developers to deal with.
A culture of optimising the elegance of the API over the simplicity and maintenance of the implementation.
Source: Maintained a 300 kLOC Perl application for 3 years, now working with legacy and new Rails applications.
I'd also add D (above C++, level with Java) and Rust (above C++, close to Go).
FWIW, here's the Go project lead congratulating Rust on their recent birthday: https://twitter.com/_rsc/status/732379957129826305
I think what they were trying to show is whether languages are high or low level (i.e. how far are they from machine code). In C for example every statement (maybe except switch) you can guess what assembly code it would translate to. Not so much with languages on top.