Maybe there were not actually valuable to the visitors?
So even though they created something of value (otherwise it wouldn't be on the front page) but most people still won't pay for the content.
Patreon works the same way. You make money when you produce content that people want to pay for even if they don't have to. If you can't do that, ads are a fine plan B, but you have to go into that knowing that many people will be ad blocking (and even more if you're producing any kind of technical content).