Not using 'like' for similes --- where does this come from? [closed]

I just got back some feedback on a piece of work of mine from a proofreader. One of his comments is that I use like in similes a lot, and I shouldn't do that --- I should be using as if instead; he says that like most accurately means is similar to. For example, in this phrase I used:

It accelerated away like a bullet down the barrel of a gun.

I've never come across this before. I know that my proofreader speaks fairly old-fashioned British English, and I speak fairly modern British English, and as far as I'm aware, like is perfectly acceptable here. But I'm not aware that it was ever not acceptable (in relatively recent times).

Can anyone find my a reference for what he's talking about here? Some basic searching doesn't come up with anything, but like is practically ungoogleable.

You can find this advice at Grammar Girl, and probably many other places on the internet. The rule (which seems to have been generally followed before the 20th century) is: use as if when it introduces a clause containing a verb, and like when it introduces a noun phrase.

Consider one of Grammar Girl's examples. The first two are both correct, while the third is supposedly wrong:

He throws like a raccoon.

He throws as if he were a raccoon.

*He throws like he was a raccoon.

In the 19th century, Google Ngrams shows that people never (or very rarely) used like for clauses containing verbs. So this was good advice in the early part of the 20th century, when this use of like was grammatically new, and would have been considered out of place if used in formal writing.

Now, the grammar has changed, and like sounds perfectly fine in these sentences to me. However, you still get people promulgating this rule. And it looks like some of them (like your proofreader), for whom this rule is not part of their natural grammar, have overgeneralized it to never use like in similes. This was never a rule of English grammar.