Suppose a company wants to write some product documentation so customers and prospective customers know what features their product has and how to use them. They hire someone to write the documentation and then someone else to distribute it. Is there a good way to distinguish this from advertising?
The most plausible way would be if the one you're paying to distribute it has some kind of exclusive control or market power over the distribution channel so that you're paying them a premium over competing distributors. But then wouldn't the best way to prevent them from extracting that premium to be to make it so nobody has exclusive control over distribution channels, e.g. by breaking up concentrated markets or requiring federated protocols?
>Suppose a company wants to write some product documentation so customers and prospective customers know what features their product has and how to use them. They hire someone to write the documentation and then someone else to distribute it. Is there a good way to distinguish this from advertising?
Yes. You self host it as a company, and it can only be reproduced (if they wish) in outlets (say review sites) when there's no payment or compensation of any kind involved for that.
There are legal definitions of advertising, I’m sure the courts will be able to figure it out.
Advertising is a monetary transaction between an advertiser and a publisher. The customer (or product) is not involved in the transaction; it is their attention that is being bought and sold.
That's a different model than paying a technical writer to do technical writing.