Writing for humans and machines at once
You no longer write only for readers. You write for readers and the engines that summarize you — and the good news is they want the same things.
Content used to have one audience: people. Now it has two — the humans who read it and the engines that crawl, rank, and summarize it. That sounds like a tension, like you'd have to choose between writing well and writing for machines. Mostly, you don't.
Clarity serves both
What makes content good for an answer engine — clear structure, direct claims, leading with the point, genuine substance — is exactly what makes it good for a busy human too. The old game of stuffing keywords for machines at the expense of readers is dead. Today the machines reward the same clarity readers always wanted.
Where they differ, add structure
The small extra you do for machines is structure they can parse: clean headings, structured data, semantic markup. None of it hurts the human reader; it's invisible to them. So the practical answer is to write genuinely well for people, then add the machine-readable scaffolding on top. One piece, two audiences, no compromise.
Write clearly for the reader and you've already done most of the work for the machine. They want the same thing.