There are separate sections for those things, called territories. I own the econ territory and co-own sports. I agree that discoverability from the front page could be improved.
If someone spends more on posting fees than they receive in zaps, it means they aren't adding value to the readers. That they cease posting is sort of the point of a market economy. Extra pressure to consider what value you're adding is another feature that people sometimes see as a bug.
That said, most of us do want people to have some sort of ration of free posts, like one per day.
