People reading what I write are frequently users of English as a second language.

Expecting most of the English people to know obviate is pushing it, for someone using English as a second language it’s just adding complexity.

It’s about aiming where you expect the average reader to be.

Because you know the word don’t fall into the trap of assuming everyone else does.

Many times it's the other way around.

Obviate has several cognates in romance languages, so it is straightforward.

Now, the phrasal verbs that are so obvious to a native speaker, these are the real head-scratchers.

Or street slang. It may sound like dumbing it down to you, but it actually adds complexity for a non-native.

Indeed.

"Register": I immediately know what it means and it takes tenths of a second for me to make the decision to click (or not to).

"Sign up": despite having a CEFR C2 level of English and using it at work every day, I still need to think for a few seconds if this is a registration or a login (cf. "sign in").

For a native speaker I suppose the latter is (marginally?) easier, but for a non-native, it's much harder, not even close.

Your examples are very illustrative, but I would argue that both phrases suffer from being too generic. I wish that there wasn’t such a push for “one word” CTAs. Examples of alternatives I’d advocate for depending on context:

“Create an account”

“Subscribe to mailing list”

“Submit contest entry”

Treating everyone like an idiot is just doing you and them a disservice. The word exists for a reason, use it.

As a native speaker, it's very unpleasant to write like that. I will if necessary for effective communication, but it's like wearing a straitjacket. It can be awful to read, too. Rarer synonyms and the phrasal verbs (both commonly avoided in a simple style) are sometimes necessary to avoid excessive repetition.

It is one of the downsides of being a native speaker. I write pretty much like how I speak. It's hard to use it like a foreign language, but that's what technical international English feels like to me, in a way. In my experience, fluent second language learners master that style more easily than native speakers do.

> This was a tradeoff to appeal to people whose vocabulary is narrow, not improve comprehension.

”Comprehension” is not some audience-independent property of a text. Comprehension is what happens when a text is well-calibrated for an audience. If your audience is unlikely to know the word ”obviate” (which seems true of many engineering settings, where the audience is international), you absolutely improve comprehension by replacing it with words the audience is more likely to know.

I agree with you that ”obviate” sounds better, and in a setting like a blog post, monograph, or even an hn comment, that’s probably what I’d use. But in e.g. a work email for colleagues in another country, you reduce the risk of miscommunication by following OP’s suggestion.

Isn't that how communication works? Understanding your audience and "appealing" to them does improve comprehension for them.

> your audience

There lies the spring coil. The less it is established what your audience is, the more you shift from "calibrated expression" to a form of expression which is as absolute and universal as possible. (See my previous post here, at https://news.ycombinator.com/item?id=33045225 .) If you have a message for an audience, you will try and condition its expression according the audience; the more the audience is abstract, the more the expression will be unconditioned, as if intended for an ideal audience.

Yeah, using words you're sure your audience knows just is communication, to me.

That said, there is of course a gray zone here.