I'm not sure what you mean by that. First, at the time you couldn't find stuff like that online. I'm talking, legit course from legit professors for free.
Then about the audience? I personally was a student when Coursera became a thing and I got into my masters by taking the course on cryptography. I have many student friends at the time who learned a lot through other courses.
Many people thought it was anyway.
In practice, it ended up being mostly another source of lecture videos used by motivated professionals with generally solid fundamentals. For which, frankly, there were already a lot of resources out there.