...which is just a modern way of saying "sales agent", yes?

It's muddy, because AFAIK, anyone can write on Medium, so it's not immediately recognizable as marketing, correct? Which, I presume, is also part of the strategy.

It's a legit strategy, it's just that one needs to keep in mind to second-guess everything the author says, since it could be a paid ad. Something, something along the lines of commercial and independent reviewers. I guess it's a never-ending war that must be fought.