Don’t confuse "being paid for your popular content" and "people paying actual money for your content". On Quora you get paid for your popular content even if nobody willingly gave you money: it’s just that the website is now full of ads and you get a small percentage of that.

The quality problems often come from the poor proxy. Money being fungible means that the rich get higher weight in determining what's considered valuable. In this marketized system, who will value journalism - especially the kind that people in power need to hear, not what they want to hear. If the rich want to suppress a fact, they can buy fake news - and because price = value, the fake news becomes the new truth.

Quality of content is not quite "subjective" in general. Perhaps in entertainment.

Monetary value is not quality either.

Quality is of course subjective, but there are certainly examples of things which are popular and trashy, or cost lots of money and are not high quality, and even some examples of things which are popular and trashy and cost lots of money but are not high quality (Melania Trump's interior design comes to mind).