The question is who failed to understand floating point: The authors of the JS specification, the authors of the JS runtime, or the people writing the javascript that demonstrates the 'wtf'? Is the answer "all three"?
0.1 + 0.2 === 0.3 // false
I'd say that whoever posted that needs a lesson in how floating point works.
There's no language that lets you do real-world work with numbers like sqrt(2) or PI without understanding precision and representation to some degree.
>>> from decimal import *
>>> Decimal('0.3') == Decimal('0.1') + Decimal('0.2')
True
>>> Decimal('NaN') == Decimal('NaN')
False
>>>However, your code example makes the excellent point that python has such a library available, whereas Javascript does not. At least, not as easily as an import.
I can see that some of the design decisions in IEEE-754, like NaN not beeing equal to NaN might seem unintuitive, but it has nothing to do with JavaScript - the standard is implemented by numerous languages and hardware.
That large numbers are rounded to a limited precision should not even be wtf if you think about it for a moment. Otherwise a single use of PI would fill up all the computer memory.