"[Free, open-source software] is why we can't have nice things" ...?
2048 exploded because anyone could modify it, create a doge version, create an AI version, a multiplayer version, an inverted version ...
And they did. The formula was ridiculously simple, so it was easy to do.
You can't do that with Threes. It's proprietary. You can't take it apart. You can't mess around with it. The only thing you can do with it is play Threes.
Even though none of the lines really need documentation, having the comment ensures that you can quickly jump in when you come back later.
This is really useful in something like drawing code.