Other languages have problems, but before some basic libraries (jQuery/Underscore) and language enhancements (Typescript/Coffeescript), it was arguably quite simplistic, and parts of the language were straight up anachronistic.

If you've ever been unfortunate enough to have to wrangle a VB script routine, it was (less bad) like that. If not, I would go find some assembly code and teach it yourself, and then imagine that instead of side effects in registers there were random effects on your code/visual state.

And like assembly code, you could now imagine that the same code might behave wildly different on different machines in different browsers.

So a bit of "old man"isms, but also I imagine his JavaScript was tainted by the early days. It's better in some ways now, worse in different ways, I don't mean to say that is the worst or the best, just to offer perspective on where it came from.