> Using "chew" rather than "masticate" is not talking to someone like they are a toddler though.

> It's the usual way you would explain the action to someone else.

How exactly are you contrasting these? Which words do you think toddlers are likely to know?

If I say I'm talking to someone like they're a toddler the point of that is I'm speaking differently than I would to an adult. Using the word "chew" would not be something I'd avoid if talking to an adult.

For example, "hi, how are you?" Is something you could say to an adult or a child. It's not "speaking to someone like they are a child" though.

Does that make sense?

But correcting the original "masticate" to "chew" is an adjustment you make based on the mentality I described. As multiple comments have pointed out, "masticate" is not generally more difficult for a second-language speaker to understand than "chew" is, and in some common cases (Spanish, French...) it's considerably easier. The correction was targeted at native speakers, on the theory that they had limited vocabulary, but justified as if it was targeted at foreigners. If the intention was really to benefit foreigners, that impulse was misplaced, for exactly the reasons I detailed.

> For example, "hi, how are you?" Is something you could say to an adult or a child. It's not "speaking to someone like they are a child" though.

The example we have here is more along these lines:

A: Salutations!

A: Oh, I'm sorry -- I meant, "how are you?"

This is an example of speaking to someone like they are a child. You come out with a natural (for you)[1] word choice, and then pre-emptively decide your interlocutor can't handle it, so you adjust to something you believe is simpler. You are speaking differently than you would normally.

[1] http://www.basicinstructions.net/basic-instructions/2009/1/2...

I think the suggestions is that toddlers know the word "chew" but not the word "masticate". Is this hard to believe?

My point was that I and most others would use the word "chew" when talking to adults in general conversation, it's not a childish word.

I was agreeing with you