Not really. He's just using that to note that JS is not really a Lispy language because of this. My choice for "why JS != Lisp" is how the Array functions return whatever you passed to them and not the array itself, so you can't write single-expression multi-modifications to an array. Unless you use the hellish Array.splice method. Which I'd argue is even worse.

"It takes time and effort to master" - Yes, but as we know this is accidental rather than essential.

How's this accidental and not essential?

Actually, if you don't know how ((this)) works in different context, you can't call yourself a good js developer.