No-one is talking about "banning", it's a bit weird you'd use that word. But that you missed that the article doesn't have the word "boy" is the reason people object to the word "girl" in that context.
As to why the article does not use the word boy:
1. As I said, such terms are usually used as endearment, for the group you belong to. Phrases like "Us girls can program, too", or "Boys, let's go get this YC interview" are common and you cannot replace women and men in these contexts. I think the OP was using girl in this sense in her post.
2. The correct counterpart to the use of girl seems to be guy (although there are phrases like "old boy's network", etc.) mainly, I think, because of alliteration. Some opponents to sexist language are offended by guy, too.
To reiterate my point, as hackers let us think about and then act rather than regurgitate rules that may be dictated by others. Let us not do simple string matching for offensive words but set our regular expressions wide to check the context that words are being used.
P.S. An interesting parallel to this discussion would be the debate on the use of the N-word, which is considered taboo by many but used by others freely.
But again, I think it's frankly weird that when someone makes a request for consensus you start talking about "rules" that are "dictated" that "ban" speech. Would you call a co-worker who was older than you "mum"? Probably not. Are you "banned" from doing so? No. Was that a "rule" that was "dictated"? No.
I'll just point this out:
The words "boy" and "girl" are usually used for endearment The correct counterpart to the use of girl seems to be guy
From my point of view (and I don't mean this insultingly--I have felt almost identically and it wasn't out of malice), your concern to not be dictated to is not a resistance to authority but an (unconscious) attempt to perpetuate a sexist status quo.
I felt similarly that the original comment was not a request for consensus, but more of a loaded question implying that it's never ok to call an adult woman a girl (which is why I asked the OP to elaborate elsewhere in the thread).